I asked this mostly for self help books, like time management and others. Obv you would need to remember and act what was discussed in the book to get any benefit from that.
You're supposed to read these books multiple times. You read the first time to get a general understanding. And then you reference things within the book as they pop up as ideas you want to remember more about. No one remembers the details of anything they read the first time. It's about constant exposure. Some things however, are important for shaping your general thought processes, but not important enough to remember specifically