To me it's very easy: If I want to do a change by hand for the joy of doing that, I do. But if I want a piece of functionality now and don't want to set aside time to build it, I let an agent do it.

It boils down to whether I dream about the outcome or how to do it.

E.g. I have no emotional attachment to my window manager - I wrote it (by hand, originally) because I wanted a specific set of functionality, not because I particularly wanted the experience of writing one.

I've recently made lots of changes to it with Opus because I wanted another set of functionality and was elated not to have to spend time doing it manually because what I wanted was the functionality.

I'm now a very happy user of a better window manager than I was before.

Conversely, I have dozens of projects I stay closer to, because I care about the code and don't particularly care if that means I might have to wait for years to get to something usable, if ever.