A writer once told me he doesn't look at his books once they are published, because he sees where more editing could be done. I suspect it is like this in all the arts. Michelangelo might look at the Pieta today and sigh, "there's a rough spot. Where's a chisel?"
Therefore, this is now my guide when editing my own work. (I don't know who said it, but it's brilliant): "An author never finishes his work; he abandons it."
If you're a writer, you're probably nodding your head. Yep, that's how it feels. At some point...we're just done. Our piece might be edited by others and maybe changed into a whole other story/essay/whatever. But, at some point....you decide to lay it down and walk way. There's closure in your heart, and what you've written now belongs to the world. At some point, we have to stop tinkering.
Like Michelangelo did with the Pieta.
He then went on to paint the Sistine Chapel.
The point? Keep moving forward.