I've experienced this with making music and editing photos, I'm sure people who paint and draw have also: when do you know when you're done? When do you accept that a little extra tweak here and a change there isn't going to make things better?

I've been working on some generative 'art' using JavaScript canvas today, and I keep finding myself making little changes throughout the day, before undoing them and going back to where I was. I know that I'm at the point where it's best to ignore it for a couple of days and come back with fresher eyes, but apparently I don't know this well enough.

I never have this with writing, even on longer form technical posts. I write, I publish after one proof read. I don't look again. In fact, it's likely no one will ever read this.