There seems to be minimum book size that forces inflation in a whole genre of self-help books that genuinely have good advice. I've read books where all of the advice I need is in the end-of-chapter checklists.

On one hand, it's good to err on the side of too-long a book, as it's easier to skip fluff than to seek out more details, illustrations, and alternative phrasings that aren't in the book. On the other hand, it's annoying to have the extra weight in volume in one's book collection.