i had that same experience. most books are good but are usually replaceable. some books i can't understand how good they are because they're beyond my level. An

i had that same experience. most books are good but are usually replaceable. some books i can't understand how good they are because they're beyond my level. And a few are just right, and also take you to that "a-ha moment." you need to do your research and select that one right book and work through it. If in the middle of a book you think you're not making good progress, you should just drop it and find another one.