I and many others have read the whole thing.. some of us have also read it through multiple times. If you are reading it and being exposed to material for the first time than obviously it is going to take a while to get through the thing but once you actually understand the information, you can read through the whole book in an afternoon to refresh your mind. It's like you're not even reading because your mind is telling you what the book is going to say next. Then when your mind lies to you, you know where you should spend an extra 15 minutes of your time. 👍
As for the lab stuff, I didn't read any of that. I did however use all their AP exams and also ordered the additional exams from Cliffs. Being exposed to all those extra questions really helps.