Not including short story collections, poetry collections, anthologies, etc.
For me, I believe it’s Oroonoko by Aphra Behn because it was on the syllabus for three different classes that I took in college. Other than that, the most I’ve read a single book is twice, and that was Telegraph Avenue by Michael Chabon. I’ve read Dracula 1.5 times. Didn’t finish it the second time around.
That’s not a great reference spot, the author doesn’t seem to have any friends, as in he can’t even describe basic human connection in a way that isn’t sad and distant, how could a person like that have insight into the inverse or even harsher. If a sibling of mine were reading this person’s books I would keep an eye out for other NEET or MGTOW behavioral problems.