“Over and over again, we are told about the importance of polishing, of revising, of tearing up, and rewriting. I got the bewildered notion that, far from being expected to type it right the first time, as Heinlein had advised me, I was expected to type it all wrong and get it right only by the thirty-second time, if at all.
“I went home immersed in gloom and the very next time I wrote a story, I tried to tear it up. I couldn’t make myself do it. So I went over to see all the terrible things I had done, in order to revise them. To my chagrin, everything sounded great to me. (My own writing always sounds great to me.) Eventually, after wasting hours and hours–to say nothing of suffering spiritual agony—I gave it up. My stories would have to be written the way they always were—and still are.
“What is it I am saying, then? That it is wrong to revise? No, of course not—anymore than it is wrong not to revise.”
-Revisions, by Isaac Asimov, in the collection Writing Science Fiction and Fantasy: 20 Dynamic Essays by the Field’s Top Professionals.