a dream app would be one that starts as a simple list (like you did), and gradually offers you to add complexity to your system

I like your analysis of this issue, though I think in this particular case the app actually remains very simple.

If you only use the "do it every N days" type of tracking, you get pretty much just a list like the ones I used to have on paper.

One thing I'm definitely seeing more clearly after reading your comment is that if I ever want to add more complexity to this app, I'll instead make a new app that will be the "next step in evolution".

(this doesn't apply to UI improvements of course, which the app still needs a lot)

I'd like to see the whole process to how you got here in the hopes of making sense of your successes/failures of systems

Haha, this calls for a long evening in front of a fireplace :)