I always approach Nanowrimo as an exercise in spontaneous creativity. I'm what is termed a "pantser" (writing by the seat of your pants) and, unless something goes terribly wrong, whatever I write as I go stays in there. Of course, I handwrite too, so that makes it harder to tinker with scenes after you get them down. (Though I do make notes for changes that I want to make in December when I'm editing in the margins.) Of course, I don't write with any aim of being published; I just do it for fun, so that probably makes a difference. For me, the best part is at the end of the month seeing how I got to the end from the beginning when I had no idea what my course was going to be.