There’s an unwritten rule that if you work long enough on complicated enough digital product design problems, somebody will come along and think that color coding would be a great solution. It basically never is. Color coding is a sign of design weakness.
This is a great thread on how Duolingo added a step to their onboarding experience that did nothing but put the user in the right mindset to learn. They let people pick a streak goal to challenge themselves. No matter if users picked 3 or 30 days, the app didn’t actually save the data nor did it do anything with the selection.
Apparently this still resulted in a “huge” retention win. Stuff like this is my favourite kind of A/B testing. It’s not just a different shade of green that performs slightly better but a whole layer of human psychology that got revealed and used to create a win/win situation for user and company.
By the way: I did not expect much from it, but Atomic Habits is a good read. It’s not mindblowing in any way but also not as shallow as I expected.