Diagnose a retention problem

Leo — I wouldn’t double paid acquisition yet. The flat WAU is masking a retention problem, not showing that summer is the whole story.

• The active base is eroding while inflows hide it. From week 1 to week 13, new users rose from 6,034 to 7,847 (+30%), but retained users fell from 44,884 to 41,636 (−7%). Weekly churn rose from 7,116 to 10,279. WAU stayed near 52,000 because more new users—and, from week 6, more returning users—offset that loss.
• New-user retention deteriorates sharply after week 4. For the first four signup cohorts, week-4 retention was 33–34%, and week-8 retention about 30%. For cohorts in weeks 5–8, week-4 retention was 24–25%; week-5 retention was about 22%, versus about 32% for the earlier cohorts at the same age. Week-1 retention actually improved (roughly 54–55% to 58%), then users fell away faster. So sign-ups are easier to get, but fewer people build a lasting workout habit.
• The timing points to a product change worth investigating. In week 5, we removed the goal-setting step. Sign-up completion rose from 61% to 74%, while the cohort retention pattern worsened immediately. That’s strong evidence to investigate whether the change brought in less-committed users or removed useful personalization—not proof that it caused the decline. Seasonality may contribute, but it doesn’t explain away the sharp cohort break.
• Win-back lifts WAU more than durable retention. Returning users rose from about 1,000 to about 2,600 a week after the week-6 campaign. But only 12% of email-returners were active two weeks later, compared with 41% of people who returned on their own. The campaign may be adding short-lived activity, not repairing the underlying habit problem.

What I’d do before scaling spend:

1. Test the onboarding change now. A/B test restoring goal-setting (or a shorter version) against the current flow. Measure signup completion alongside week-1 activation, week-4/8 retention, and workouts completed—not just registrations.
2. Improve the first-week habit loop. Give users a clear, personalized weekly plan and a timely next-workout prompt. Track results by signup week, onboarding version, and acquisition channel.
3. Put win-back on a holdout. Measure incremental, sustained activity and Premium conversion against users who don’t receive the offer; don’t count the initial return as success.
4. Hold off on doubling acquisition. The week-9 paid increase came after the retention decline had already begun. Scale only when newer cohorts retain better and paid users show acceptable downstream value.

Fixing the leak first gives us a better chance of turning additional acquisition into durable actives rather than more short-lived sign-ups.

Weekly actives are flat because retention broke in week 5, not because of summer

To: Leo From: Activation PM Re: Why weekly actives are flat, and why we shouldn't double paid acquisition yet

Summary

Weekly actives aren't flat because of summer. Retention dropped sharply for every cohort that signed up from week 5 onward. That is the week we removed the goal-setting step from sign-up. The win-back campaign has hidden the damage by pulling back about 1,600 lapsed users a week, and most of them leave again within two weeks. Doubling acquisition now would pour more users into a bucket that leaks about a third faster than it did in July.

What's happening

1. Churn is up 40%, and it's offset by low-quality reactivations.

Weekly churn (users active last week but not this week, divided by last week's actives):

Returning users jumped from about 1,000 to about 2,600 a week in week 6, the week win-back emails started. New users are up 30%. Together these just cancel the extra churn, which is why the headline stays near 52,000.

2. The break follows sign-up cohort, not the calendar.

The change is a clean step at the week-5 cohort, with no gradual drift.

3. The evidence argues against seasonality.

• Cohorts behave differently in the same calendar weeks. If summer were the cause, everyone would dip together. Instead, the weeks 1–4 cohorts held at about 30% through all of August, while the cohorts that joined in August decayed fast.
• July was summer too. Churn was at its lowest then.
• September didn't help. Weeks 10–13 run into late September, and churn is at its worst.

4. The week-5 sign-up change is the most likely cause.

Removing "What do you want to achieve, and how many days a week?" cut sign-up from 3 minutes to 1. Completion rose from 61% to 74%. But we stopped asking users to commit to a goal and a weekly frequency, which is the core of a weekly-plan habit app.

The pattern fits: - First-week retention went up slightly (58% vs 55%), because the initial experience is fine. - From week 3 onward, users without a plan drift away.

Part of the drop may be compositional: the extra 13 points of completers may be lower intent. Either way, the cause points to the same step. Nothing else in the log lines up. The week-3 workout library shows no effect, and paid social only started in week 9.

5. The win-back campaign flatters the topline.

Only 12% of win-back returners are still active two weeks later, against 41% of users who came back on their own before the campaign. We're also giving away a free week of Premium to get them. Without the campaign, weekly actives would be roughly 1,500 lower and still falling.

Why doubling acquisition doesn't work right now

Per 1,000 sign-ups, about 300 were still active at week 8 before week 5. Now it's about 200. That means:

• We need 50% more sign-ups just to keep the same number of retained users.
• Sign-ups are up about 28%, which isn't keeping pace.
• Cost per retained user is up roughly 50% at today's acquisition cost. That's before any rise in marginal cost from doubling spend, which usually happens.

Each extra cohort loses about 80% of its users within 8 weeks. Doubling spend would mostly buy churn.

What we should do instead

1. Fix sign-up first (start this week).

Run an A/B test with three arms: - (a) the current flow; - (b) the old flow with goal-setting; - (c) goal-setting moved to after account creation, in the first session.

Option (c) could keep most of the completion gain and restore the plan. Judge the test on week-3 retention, where the gap (about 37% vs 30%) shows up within three weeks, and confirm at week 4.

If we want to move faster, we could simply revert to (b) while testing (c). We'd give back some completion, but we'd stop losing about 10 points of week-8 retention on every new cohort.

2. Hold paid acquisition at its current level until retention recovers.

Revisit once new cohorts are back to about 33% at week 4. When we do scale, check whether paid-social cohorts retain as well as organic ones. We don't yet have cohort data split by channel.

3. Put the win-back campaign behind a holdout.

Withhold the email from 20% of eligible users to measure: - true incremental weekly actives; - Premium cannibalisation; - whether the free week leads to paid conversion.

Also try a version without the free-Premium offer, or one that sends people back into a plan: "Pick your days for this week".

4. Change how we report growth.

Make cohort retention at weeks 4 and 8, plus the weekly churn rate, our headline health metrics alongside weekly actives. Report reactivations separately. A flat topline hid a 40% rise in churn for two months.

Caveats

• Causation isn't proven. The week-5 timing is strong evidence, but the A/B test is what will prove it.
• The two data sources don't quite match. Cohort sign-up counts are slightly lower than "new users" in the growth accounting (for example, 6,000 vs 6,034 in week 1), so the two may define new users slightly differently. The gap is too small to change the conclusion.

Happy to walk through the cohort curves together. I'd recommend we agree on the sign-up test before any change to the paid budget.

To: Leo | From: Activation PM | Re: Why weekly actives are flat, and why not to double paid yet

Bottom line

Summer isn't the main story. Retention of new sign-ups dropped sharply in week 5, the week we shortened sign-up. Weekly actives look flat only because more sign-ups and a win-back campaign are masking a leakier base. Doubling paid now would pour more users into a worse funnel.

What's happening

Weekly actives (WAU) went from 51,891 to 52,118 over the 13 weeks, a gain of +227. The components moved very differently:

The share of last week's actives who are still active this week fell from about 86% (week 2) to about 80% (week 13). Weekly churn rose from roughly 14% to 20%. Growth in sign-ups and returners is almost exactly cancelling a shrinking retained base.

Evidence it's the sign-up change, not summer

1. The cohort cliff is a step change. Sign-up cohorts from weeks 1–4 plateau at about 30% active by weeks 7–8. Every cohort from week 5 onward plateaus at about 20%. Week-4 retention drops from about 34% to about 25%. The break lands exactly on the week we removed the goal-setting step ("what do you want to achieve, and how many days a week?"). It doesn't appear gradually.

2. Same calendar weeks, different outcomes. Seasonality hits everyone active in a given week. In calendar week 10, the week-3 cohort (seven weeks old) is at about 30% retained. The week-6 cohort (four weeks old) is at about 24%, and it was still falling. Old cohorts held steady through August and September, so users who signed up under the old flow aren't behaving "seasonally."

3. Other changes don't fit. The week-3 workout library came before the drop and didn't move retention. The week-9 paid increase didn't change cohort quality (week 9–12 cohorts look like weeks 5–8), so the problem isn't paid traffic. It's what happens after sign-up.

4. The trade-off was a bad one. Sign-up completion rose from 61% to 74%, and week-1 retention even ticked up (about 58% vs 55%). But per 100 people starting sign-up, long-run actives fell from about 18 (61% × 30%) to about 15 (74% × 20%), roughly 19% worse. My hypothesis is that the goal and days-per-week answers fed the weekly plan, which is the core of the product. Without them, users get no plan to return to. This is inference. The change wasn't randomized, so we need to test it.

The win-back campaign is propping up the number

Returning users jumped from about 1,000 to about 2,600 a week at week 6, when win-back emails started. That's about 1,600 extra returners a week, and it's what has kept WAU flat. But only 12% of win-back returners are still active two weeks later, versus 41% of people who came back on their own before the campaign. That's roughly 190 durable users a week from about 1,600 reactivations, and it costs a free week of Premium each. Without it, WAU would be around 50,000 and visibly declining.

The comparison isn't perfectly like-for-like, because self-returners are more motivated. But the campaign is clearly adding far less durable activity than the headline suggests.

What to do instead

1. Hold paid at current levels. Don't double it. At 20% plateau retention, recovering the old 30% on about 7,500 weekly sign-ups is worth roughly 750 extra long-term actives per weekly cohort. That equals what a 50% increase in sign-ups would deliver at current quality, without spending anything.

1. A/B test restoring goal-setting, starting this week. Compare the current 1-minute flow against a version with a single "goal + days per week" screen, ideally right after account creation or at the start of the first session, so it adds seconds rather than minutes. The goal is to keep most of the completion gain and recover retention. Primary metric: week-4 retained rate. Guardrail: sign-up completion. The decision metric is retained users per 100 sign-up starts, not completion alone. Week-4 data takes about a month, so I'd also watch week-1 and week-2 retention as early signals. Then use the answers to generate the weekly plan automatically.

1. Put a holdout on win-back. Withhold the email from a random 10% of eligible users so we can measure true incremental reactivation, not just "returners." Judge it on two-week-retained reactivations and on Premium cost. Test a lighter offer or one tied to a specific plan or workout.

1. Change how we report. Show WAU split into new, returning, and retained, and add cohort week-4 retention to the weekly review. Flat WAU hid this for three months.

1. Set a gate for scaling paid. Once new cohorts' week-4 retention is back near 33% (the pre-change level), scaling acquisition is a good bet. Until then, each extra dollar buys users who mostly leave.

Caveats

• Cohort data only extends 8 weeks, and recent cohorts less. The 20% plateau is well established for weeks 5–8 cohorts and extrapolated for later ones.
• Win-back reactivations may flatter recent cohorts' later-week numbers, so the real retention gap could be slightly larger than shown.
• I don't have channel-level data, so I can't say how much of the sign-up growth is paid or whether paid cohorts differ from organic. That would be worth pulling.
• Some summer effect is plausible, but it can't explain a step change that hits only post-week-5 sign-ups.