“COMMIT. That means not even doubling back to check something. I mean it. If you forget a character's name, who cares? Make up a new one and fix it later. (In fact, that's REALLY easy to fix. Find/replace, anyone?) If you double back, even if it's just for a few minutes, you will mess up your momentum. (Probably.)”—Veronica Ruth
This is good advice whenever you’re generating a first draft, and especially important during NaNoWriMo. The point isn’t just to flail away at words to reach an arbitrary (or not-so-arbitrary goal). The point is to keep up your momentum and capture the story while it’s fresh, to gain some distance between you and the words you’ve written, so you can come back to edit with a clear idea of The Big Picture and enough objectivity to recognize what’s good and what’s not so good.