However, I have also attended some gems of talks. Second, I don't think my professors always made the best use of lectures. Detailed presentation of theorems and proofs, or even of many examples, is not the best use because the pace won't be right for most people. However, lectures can also provide an overview of the material that is very worthwhile. A lecture can't cover as much material as the corresponding sections of the book, so the professor has to distill the material.
Lectures are important for another reason.
They represent a commitment to set aside regular times during the week to fully concentrate on the subject matter. In light of the above, here is how I run classes absent contrary information from you about how you learn best. Any ways in which my approach is different from the book's. I do only a few examples or proofs in class. I refer you to the book or to handouts for more proofs, and many of the problems I assign provide further examples.