Even if I don’t directly use each book, I might find ideas and inspiration in them that I can bring back to the games I do run. This has happened plenty of times. Besides, they can be fun to read. This goes for old books too. Numerous times I’ve adapted old material for new games.
This is why I liked the how Torture skill in Burning Wheel does just this: you decide what the victim says. It’s not true, it’s just what they admit to.