Streaks are everywhere.
Streaks to “encourage” learners to come back every day to learn a language. Streaks to “encourage” players to come back to a game every day. Streaks to “encourage” people to exercise every day. Streaks to “encourage” users to message their friends every day on messaging apps.
Yeah, I was unsubtle there with my little “encourage”.
Streaks are simple behavioural psychology.
Unfortunately, they’re often implemented as little more than bribery, wrapped in negative messaging designed to make you feel that not coming back will have consequences.