NaNoWriMo can be used to create a good habit - writing every day - but it can also create some bad habits. Namely, what you consider to be progress, and how you judge yourself.
I'm struggling with this right now. I've had to take a break in writing to work on some research, and it feels like getting nothing done. NaNoWriMo teaches you to only count actual words written as progress, and researching means no writing is getting done.
But research is still important, and I didn't want to waste time writing a few very specific scenes without doing some research first. I also didn't want to keep going with the rest of the novel - which NaNoWriMo encourages, in order to prioritize the writing of words - and have to come back and research and write these scenes later, when I'm not in the flow of the story any longer. (I'm a fairly linear writer, and typically write in order of how I envision things happening in the book. This is different from writing in order of how things happen, because, for instance, I write flashbacks when the flashback happens in the story, rather than when it happened before the story took place.)
So I don't have much progress showing on my graph for a few days, but that's okay, because I was working on my novel during that period.
I've also been allowing myself breaks on the weekend, but that's a subject for another post.