@evan @tony That's yet another question though?
How much effort a given piece of software requires to stay functional in a changing world is very varied.
I have a tiny C mail delivery agent I wrote for myself in 1997 and last touched in 1998. It's still working perfectly fine locally. (I had to recompile it once.)
Compare with a project like Home Assistant, where I really couldn't guess how much effort that must be.
I'd expect a few hours per month for an average project.