From a great article titled An Oral History of The Wrens' The Meadowlands:

It is one of our maxims that has come up over time: “If you have to ask, the answer is no.” So if you’re like, “Well, is this good enough for this song? Is this the way we want the song to go?” If you’re asking, the answer is no. Because when it is right, you want to listen to it and you almost fantasize that you were in the band that is playing that song, you’re like, “Oh, I wish I was those guys. Oh wait! I am. Wait, we didn’t do this.”

I think that maxim can apply to projects, web sites, tweets and other creative endeavours.

Knowing When a Thing is Finished