Some of those repeats are more flexible, like "water my plant 10 days after I last watered it". It's not going to fall over and die if I miss a day or 2. That also lets me treat my calendar as sacred: if I have an appointment there, I have to be at that place and time. My dentist won't amused if I'm a day late.

I hate recommending specific apps, but after using OmniFocus for years, I started using Things a few months ago and it's been heavenly. It's not as powerful as OF, but has all the features I actually need and not much else. I'm not tempted to waste time making my workflow absolutely perfect and optimal instead of just, you know, doing things.