I go into NaNoWriMo without an outline. I have an idea for a story, the main character and essentially what happens. The barest of bones. I may have some notes, which is the closest I get to an outline. I jot down brainstorms, some of which won’t prove useful. I consider the opening scene. Because I write by the seat of my pants, I really only need that lead into the story, that one scene that gets me into the world. Then I write it as it comes to me, and the more I write the more glimpses I get into the overall structure, the plot points, the additional characters. I make notes as ideas arise, and keep writing the story. So NaNoWriMo is perfectly suited to me. I don’t usually write so much a day. I probably have a daily average of about a quarter of the NaNoWriMo word count the other eleven months of the year. The slower pace allows me time and head room to revise other manuscripts while still making progress on a first draft, and allows for more balance overall in my life. But for one month out of the year, it’s a rush to open the spigot wider and let a story flow through in a torrent.
At the end of the month, I have a first draft of a novel (or at least the first half, if it’s a big fat fantasy), the raw material of my craft. That’s a kind of wizardry, making something from the voices in my head.