Imagine that awesome learning app you just build. But why do users not come back although your app is so great?
Do not waste a week before sending out notifications to newly signed-up users. Test activity and behavior of cohorts that receive e.g. a welcome message the next day, the second, the third. Compare results. Repeat a week after sign-up. Align the content of each notification with the utility of your product. This is key. What is the result? Streamline and optimize engagement.