A confession (and, simultaneously, an undignified boast): I was always that kid in school who did a perfect or near-perfect first and only draft of a writing assignment. After years of voracious reading, I knew how sentences should be constructed because I had seen so many of them, and I was a good speller. From handwritten work through my typewriter years, I did one neat, well-crafted version and handed it in.
I despised the occasional assignment which required a messy, marked-up first draft and then the revised, neat, finished paper. I would always write what I needed to and then reverse engineer a rough draft to satisfy my teacher’s pedanticism. Such, then, was the state of my abilities (and my ego).
After getting a word processor, though, and discovering the endless joys of painlessly changing a word to improve a sentence, and of moving entire paragraphs around, I have become an inveterate revisionist reviser editor of my own work.
And that is how the best work is produced. The writer must go back through his story and make certain that every word, every concept is as it should be. Sometimes this will be a simple process; other times, it will mean rewriting the story essentially from scratch.