Some people [looks at JP] like reading multiple books in parallel. JP is currently reading two (three?) books in the same genre (sf). One guy I know (let’s call him “Ralmon”) reads multiple books in parallel, but only when they are different types – a sf book, a non-fiction book, etc.
I’m more of a serial reader myself. Well, maybe not entirely, since I do tend to sneak in some short fiction stories while reading novel-length stuff. Like Ralmon, reading two science fiction books in parallel is out of the question. I’m sure to confuse universes or essential plot elements. I’d constantly be asking myself why Paul Atreides just doesn’t slip off his VR mask to get off that accursed planet.