Sy Safransky has this to say about editing:
Readers sometimes ask how much I edit my own writing.
I edit until each paragraph has lost the ten pounds it gained over the winter.
I edit until each sentence can survive three days in the wilderness on its own.
My father taught me to look at a sentence and, if it didn’t deserve to live, shoot it between the eyes.
Sy Safransky, The Sun Magazine, May 2011