That entirely depends on the book (but not the subject matter). There's some books that i read once and am constantly recalling things from, there's other book

That entirely depends on the book (but not the subject matter). There's some books that i read once and am constantly recalling things from, there's other books that i can read a couple times, feel like i'm understanding or enjoying it while reading it, and then a couple weeks later i can't remember it at all. This holds true for me across technical, non-technical, and fiction. Writing memorably is a skill.