tldr: limiting the books one reads by their ability to consistently entertain makes little sense and similar advice should be largely ignored
I’ve seen some posts/advice pop up multiple times over the past month that recommend dropping books that you don’t enjoy and understood the direction they were going in, but don’t really agree. If reading is purely a leisure activity for someone then it makes sense that they might come to the conclusion that they should, as a rule, drop a book as soon as they lose interest or get bored. But this restricts the type of enjoyment one can receive from a book to a very narrow definition of enjoyment.
If one is only looking for constant entertainment from a book then the number of books one can read is vastly limited. Books previously enjoyed might never be read again because of changing tastes or simply because it has already been read which is a tragedy in itself because of how much value books can provide on the 2nd, 3rd read. Instead, difficult and seemingly boring books should be embraced along with the purely entertaining books.
Difficult reads can provide a significant amount of enjoyment in non-traditional ways: they can be opportunities to practice persistence and focus, they can be sobering or humbling (especially if they deal with lesser known areas), they can be intellectually expansive and many other things! Even if a book doesn’t seem to fit your current idea of enjoyment, with a little thinking a reason can be found for at least trying to wade through the mire of boredom that sometimes appears in books. On the other side can be a number of rewarding things which one might find even better than substance that provides constant enjoyment. The one area to watch out for, though is reading too many books in succession that are “heavy” or that leave you struggling with intrusive thoughts.
Reading a book that deals with very mature or disturbing content can be positive in some respects, but without breaks it can potentially affect one’s mental state negatively. Depending on one’s ability to process difficult or disturbing material, someone could end up “over-served” when life events are added on top which can cause more pain than is necessary for such books. Taking time to check in with yourself is important and mixing in lighter or instructional books can help prevent ending up in an unhealthy state.
In the end, books and the enjoyment one gets from them should be tailored to the individual. Though one might end up pleasantly surprised if they are willing to experiment and push into some areas of discomfort every now and then.