Smooth difficulty in learning paths, address hurdles
There are some songs where I got stuck for a long time, because I think the difficulty increased too much. You could check at which songs people need more time to complete them and implement measures to make it easier.
For example the fingerpicking for guitar section: There is a simple trainer and then the second next song (cowboy exit music) immediately uses difficult fingerpicking patterns. There are some great fingerpicking workouts in the app that range from easy to hard. But they are not part of learning path and you have to find them first. In my opinion they should be placed before the song.
Also sometimes the new technique is difficult and I hate the song, which really demotivates me from learning that technique with that song. Would be great to have a joker once in a while to skip a song.