Okay, it's likely a combination of all of those factors, if I'm being perfectly honest with you (and with myself). But, in an effort to keep my wandering mind somewhat focused on the task at hand -- Gadda's Quer pasticciaccio in Via Merulana (That Awful Mess on the Via Merulana) -- I just read a really insightful article on Newsweek again, by David Gates, about the "Pleasures of Rereading."
You can read the article here.
There are some books I have read over and over, sometimes for enjoyment and sometimes because multiple classes assign the same books from semester to semester. But really, what is the harm in that? I learn something different each time I pick up Gadda (begrudgingly) or Svevo (happily); each class offers new insight, each professor offers a new point of reference for the book, and I'm learning to appreciate books more on the second time around. Besides, some books can only be re-read, like Ulysses. Which is amazing, the second time.