Waddaya mean, rewrite? Rework bits as I go, yes, a hundred times if necessary: an excellent way of getting into the mood to write the next bit. Edit as I go, edit after I've gone, most certainly-- I write to edit as Kurosawa shot to edit. But start from the beginning and do huge chunks all over again, if not actually write the whole thing a second time from scratch? No way, man. What's written is written, and if it doesn't work as written, tough. Maybe the next story will.