Here is a great article from Publishing Talk regarding NaNoWriMo and similar writing challenges.
My favorite part of the article is what the author, Sarah Salway says about an excerpt from Art and Fear:
It reminds me of a famous experiment outlined in the book Art and Fear,
where a college professor divided a pottery class. Half had to produce
just one perfect pot; the other half as many as they could. Surprise,
surprise, the better pots were to be found in the second group – those
who went for quantity over quality.
This is what writing challenges focus on. Just getting stuff on the page and getting the editor living in your left brain to shut up and let you create.