What goes in a brand book, and what can stay out

Most brand books are too long. The ones people actually open answer the questions that come up when someone has to make something: which logo, which red, which font, how big (sample post).
We start from a list of the things your team will make in the next year, then write only the pages they need. A bakery needs a label chapter; a festival needs wayfinding.
Everything else (the mood boards, the routes we did not choose) goes into a project archive, not the book.