I can see that being an issue. I'm in the same habit with LOTR, ASOIAF and Harry Potter, reading each series once every two years or so, and it crushes my ability to read a lot of new books. I've avoided rereading Discworld so far because I know that it will never be as magical as the first read through.

But oh god, Baroque Cycle was unparalleled from a character-building perspective. I loved every second of it.