I find that a lot of people in the software field confuse maximizing information density with finding valuable learning materials.
Almost all books have relatively low information density. You can condense "How to Win Friends and Influence People" down to a page of chapter headings, for example, or a history book into a 2-3 page timeline. The point of all of the anecdotes and details isn't to convey more information, it's to force the reader to slow down to think about the topic and provide more memory hooks to help with recall later.
Whenever you read a book, if you think "that was obvious, I knew that already," observe if you are actually acting on that knowledge the way you want to. After reading the book, do you act on that knowledge you already knew more easily?
Even books that are outright bad can be useful if they force you to think more about a topic and re-evaluate your own opinions. For example, I try to read 1-2 general software books a year. Some of them are terrible, most of them tell me things I already learned, but the spaced repetition makes me re-evaluate my own recent choices to see if there are any areas where I have been getting lazy and cutting corners I shouldn't.