I've been doing this thing recently where I'll make a list of the chapters in the book and every time I finish a chapter I'll write a small summary and even highlight it a color that feels appropriate if I feel it would help me remember it better. I'll show you what I mean.
https://app.gemoo.com/share/image-annotation/588238791721803776?codeId=M0GjoRpKApJBa&origin=imageurlgenerator&card=588238789981167616
This series had 5 books so after every chapter I tried to summarize it as succinctly as I could.
What I noticed is that this helped me memorize so much more than I usually do about a book. Because I'm always coming back to the list as I progress thru the book, I spend more time looking at how the story is structured, how the pacing has been, and where I think the story might go next.
Plus if I ever in the future forget details, I'm sure looking over this will quickly refresh me.
Do you take any notes? It's obviously not necessary, but it seems to help.
I do, it helps me concentrate when reading. I do write down all details, just a few points that I find interesting or actionable.