The D1 Problem vs. the Week-4 Problem: Why Your Retention Fix Isn’t Working

On the surface, retention seems like a simple game: users leave, so the goal is to bring them back. However, at scale, retention is a lot more complicated. Users disengage at different points and for a wide range of reasons. It is imperative that companies are solving the right problem and targeting these moments.

At Sweatcoin, User Engagement Lead, Adele Marevery, has seen this challenge firsthand. With hundreds of millions of downloads and millions of daily active users, the focus has shifted from simply acquiring users to creating lasting engagement.

“Downloads don’t pay the bills,” says Adele. “Without retention, without scale, you just become another fleeting number instead of real lasting value.”

The key is understanding that retention has two different battles: the D1 problem and the Week-4 problem.

The D1 Problem: Winning the First Week

The first retention challenge companies are facing is activation. Once a user downloads the app and does not experience any value, they will leave. 

“The first week is definitely where the battle is either won or lost,” explains Adele. “If users don’t find a real value moment fast, they will disappear.”

Many companies try to solve this with more messaging, but if users never understand the product’s value, no notification will bring them back.

At Sweatcoin, the team focused on personalized activation journeys based on user behaviour rather than treating every new user the same.

As Adele explains, “My mom would need a little more hand holding with Sweatcoin because she would open the app and feel overwhelmed with all of the features we have. Myself, I'm more tech savvy, if you give me tutorials, I would just skip, skip.”

The result was a 9% uplift in interaction with the core activation feature.

The Week-4 Problem: Building Habits

Activation gets users started. Retention comes from turning that value into a habit.

The Week-4 problem is not about whether users understand the product, it is whether the product has become part of their routine and is ingrained into their everyday life.

“Building habits and not just features” is one of Adele’s core lessons. “The product is the body and lifecycle marketing is the hands and the feet,” says Adele.

Through push notifications, emails, and in-app messages, companies can reinforce behaviours and create habit loops around action, reward, and progress.

For Sweatcoin, features like streaks become even more powerful when lifecycle marketing helps users maintain them at the right moment.

Retention Requires Relevance

Churn requires different reactivation approaches and is not just one behaviour.

“A user might not have churned for the same reason,” says Adele.

A highly engaged user who disappears for a week needs a different approach from a casual user who returns monthly. Sweatcoin improved reactivation by moving away from generic win-back campaigns and creating journeys based on user behaviour and inactivity patterns.

The result was a 53% uplift in reactivation.

The lesson is simple: retention is not about sending more messages. It is about understanding where users are and giving them the right experience at the right time.

The D1 problem requires better activation. The Week-4 problem requires better habit-building.

Solving both is how growth becomes sustainable.