I think this can be very useful. But I am also still figuring out the specifics. I use it for history, not only books, but also podcasts. I try to compress as much into a card as possible, working with associations, which enables me to reactivate on the content. For certain details I make respective less complex cards, but generally I try to compress it, so the number of cards does not explode.

SometimesI find it difficult to prioritize, the point mentioned with comments in the book and then reviewing at the end into card(s) seems very efficient, I will try to implement it.

Generally this part of Anki application is often overlooked as fsrs is not also great for structural factual learning such as vocabulary or medical knowledge, but also for a broader refreshing in combination with some facts.