After doing a final edit, send the piece on its way. Too many writers get bogged down here. Nothing will ever be perfect, so let the piece go. If you are truly unsure, and believe one more edit is necessary, put it aside for a whole week. Then take it out one more time for a final check.
Some writers hesitate in sending out their finished work because deep down they fear rejection.
It becomes easier to imagine the success of your writing, than it is put it out there for someone else's approval. But this attitude is self-defeating. If you find yourself wavering when it comes time to send your work out, then set a deadline for sending it off. Then stick to it. Some writers never struggle with rewriting or over-editing.