I have a tendency to read books too quickly. It might be “reading in my head” taken to its logical extreme, or the abuse of paper-skimming techniques, but when I read fiction (particularly exciting fiction), I skip over whole lines at a time, subconsciously scanning for the next piece of plot or action. I don't think this is very good. I miss out on important plot details, and also on actually reading a not-insignificant part of the book.
Recently, prompted by one of those “me and pookie”-esque Instagram reels which survives by being forwarded around in DMs between young lovers, like some sort of memetic STD, I tried reading part of my current book out loud, to my girlfriend, just as we went to bed. I highly recommend this: it's much better than reading a book to yourself by the light of a smartphone, it's intimate and cozy, and it forces you to read every word, at an even pace. I was surprised that, for several days after doing this, I found myself reading the book much more carefully, at a slower pace, and was much more able to appreciate subtler parts of the text, as well as to notice and later remember small but important details (Chekhov's Gun is all very well, but John le Carré makes you keep an eye out for Chekhov's Cigarette and Chekhov's Hat as well).
So, in summary, I highly recommend reading a book out loud, to anyone who will let you do it.