As a contrast to the Tolkien position, it is said that James Joyce felt that a trufan should read nothing but James Joyce, round and around we go again...

(Further to what is not quite the same point, I know a Booker winner who belongs to a book group, but it's a bit more specialised than that: it's a Henry James book group. They just read Henry James, one book a month, and when they get to the end of the oeuvre they go back to the beginning and begin again.)