In any creative endeavor, or even professional endeavor where you have to polish a project or proposal, there is this feeling that you can do just a little bit more to make it better. Just another pass to clean up the lines. A quick edit to make sure the flow is right. Another look over to make sure you have no typos in your proposal for how to train people in the use of the Spell Check feature of a word processor.
Just another, a little, a bit, more, more, more, more. The thing is, once you've fallen into that trap you're never going to be finished. It could always be better with just a bit more work, and it will never be perfect, which is what your brain is trying to do. In that regard while you are going for perfection you will never be done, which is a fancy way of saying that for something to be done it can't be perfect.
But that leaves the question of how good is good enough? "Good enough" as a phrase kind of has a negative connotation to it. We don't say something is "good enough" when it is actually good, we say it when we want to justify something. "It's good enough considering..." or "It's good enough for a first effort" or even "It's good enough to be a blog post."
Somewhere in the middle is where your project needs to be.
If you're writing, the middle is not "after the first draft." I mean, not unless you want it to look hideous and be full of mistakes you didn't notice.
The same is true for any art, and even simple things like e-mails. Find the right spot in the middle, but remember it can't be perfect and at some point it does have to be good enough.