Importance of Drafting

The intention with NaNoWriMo is to get you your first draft of your novel-to-be. Draft is for a novel like a sketch for a painting.

Look at the following sketches by Leonardo da Vinci.

Sketches for Leda's head. The last one isn't even called "sketch for Leda's head", it's "sketch of a young woman". The topmost are sketches of Leda's hair.
These are "rough sketches", more like the character worksheets and detailed outline for your novel, than the first draft.
An artist's sketchbook is like a writer's journal.

Sketch and painting for kneeling Leda. Now we are getting to the first draft stage. The sketch painting is already a full painting, but it's still just a sketch. Your NaNoWriMo novel will be this. You are probably going to change quite a lot about your draft in later stages of writing a novel.

Like Leonardo did with his Leda. The final version is in the middle. Around it are some more "drafts". He was experimenting with the ideas. He painted Leda over and over again, changing details and even bigger parts, like the whole background, before he was satisfied with the results.

First Draft of a Paper
Importance of sketching for design
the importance of sketching
the importance of the sketch book for an artist
writing a rough draft

"Nothing feels better than printing out that completed first draft of a novel. You’ve completed that journey through the story, getting to know and growing with your characters along the way. While not perfect yet, or ready for submission, it’s a big step and one to encourage beginning writer’s to keep working."
- Julie Clements