My reading has declined as I've aged, generally, and the number of books I want to read is expanding exponentially with each passing day (and the rate at which I buy books that pile up unread is a within striking distance of being a problem. I'm a pack-rat by nature and always have been however it's becoming a bit much but also I'll never be able to resell or give away a book I bought and then didn't read. What if I get around to reading i some day? For instance I subscribed to a fiction magazine in 2018, read two of the issues. The rest are sandwiched in the middle of a pile of books which I also haven't read and have been sitting on the corner of my desk since at least 2018) so most of my re-reading was something I did as a teenager.
I also established a habit in those years that continues to this day. As a teenager I loved Harry Potter. I probably read all the physical books twice. But I owned all the audiobooks (at that time on cassette) narrated by Jim Dale and I listened to those many times. I have no idea how many. I might've listened to the whole series ten times (except Deathly Hollows, which I never owned as a physical audiobook, and I think I read it once at release and then listened to it on audible a few years later). The only other books I can remember re-reading during this time was Brian Jacques (of Redwall fame) Castaways of the Flying Dutchman trilogy, and Nancy Farmer's YA Norse mythology-inspired Fantasy series Sea of Trolls. I guess I read and re-read some of R.A Salvatore's Forgotten Realms novels. Probably a few others along the same line that I'm forgetting now.
In my 20s my favorite books were still fantasy, but now they were Glen Cook's The Black Company then-nine-book series (now ten books) of '80s-'90s trippy dark military fantasy and Joe Abercrombie's then-six-book The First Law series of '00s cynical dark heroic fantasy (now ten books). I've only actually read each of these once. But I like the audiobook narrators for each series, so I've listened to each at least three times.
The one outlier is ASOIAF. I'd read most of the books as a teenager (A Dance With Dragons wasn't out yet). Then after the show ended I re-read the books. It probably helps that I can't stand the narrator of those books, the late Roy Dotrice. Though Harry Lloyd, who played Daenerys's brother Viserys in season one of GOT, read Martin's A Knight of the Seven Kingdom novella series, and he's very good. I guess I've re-read that one too, in that I've read it and listened to the audiobook.
I know it’s just a meme, but every time I see DHMO I think of heavy water.