Do people really finish these books cover to cover? I have been working on Bishop's PRML, and it is extremely time consuming to really finish the book, and do

Do people really finish these books cover to cover? I have been working on Bishop's PRML, and it is extremely time consuming to really finish the book, and do all the exercises. I saw a blog from a guy who did the same, and it took him 1500+ hours. Not a single person in my masters program finished any of these books. They just did the courses and googled whatever else was necessary.