I have a friend who actually DID use the bingo prompts to flesh out chapters in her book. THAT said, world building is important. As is character building. When you have the stories, they can be referenced in the actual novel with a sentence or even an eyebrow twitch, and even if you NEVER TELL THE NOVEL READERS what is behind that thing, they/we will know there is something there, and that something is real, as real as anything that the novel contains.

*deep breath* Which is to say, to the 'not writing a novel in a month' brain? NINJA, PLEASE!