My work generally passes through three distinct phases. First, it is a rough draft--rough like sandpaper. Then I edit it a bit until it is "not embarrassing," at which point I can show it to people. Then there is the final stage: ready to send out to publishers/agents/editors.
I struggle with impatience, so working my way from rough draft to ready-to-send is incredibly trying. Right now, for example, I have a story that's in phase two. I have showed it to some people and gotten some good feedback. At this point, I have two choices. I can whip it into shape right away and send it out tomorrow...or I can sit on the story.
Sitting on the story has a number of advantages. In particular, letting the story rest gives your mind a chance to distance itself from the work. That way, when you come back to read the piece, you see what you actually wrote as opposed to what you think you wrote. That is a pretty important distinction, and an important part of the writing craft.
Unfortunately, this means I have to wait to send out that story. Oh, well. I should be grading anyway.