Not mentioned, but obviously you don't need to read the whole book with same depth. Almost no book is must read from beginning to end. After skimming 3-5 hours, you can decide how much of it is important, or important to you and focus on those in deeper passes.
Active vs. Passive Reading
https://owl.excelsior.edu/orc/introduction/active-reading/
https://nesslabs.com/active-reading