Oscar Wilde said "If one cannot enjoy reading a book over and over again, there is no use in reading it at all."
I used to have this obsession with always finishing a book once I started it. It didn't matter if I absolutely detested the story or the entire book itself or whatever it could have been that was distasteful. But I always finished it. This was so much the case that I still remember the few that I actually didn't finish: the 7th book of the Chronicles of Narnia, and of course Jules Verne's 20.000 Leagues Under the Sea (the movie was much easier to get through than the book...). There were always those series that I couldn't get enough of too -- like the Lemony Snicket books, the Artemis Fowl books (if they turn these into movies it will be absolutely epic), the Animorphs books, and the Time Warp Trio. I'm sure there are more that I'm forgetting... but that's not really the point.
Despite the fact it's been ages since I've read these, and I'm sure I could probably blow through them at an incredibly quick rate, I think reading them again would be enjoyable nonetheless.
Since that time and age I haven't exactly been an avid reader, and I've discussed this before, somewhere on this blog (you can take my word for it or you can spend who knows how long sifting through over 300 posts and finding it) but going back may not only be enjoyable, but a lovely nostalgic feeling.
So do you think it's true? You shouldn't read a book unless it's good enough to read again? Well in my experience -- I think I either love it, or I stop reading it partway through. Nowadays, I've realized, that especially with time constraints and so many other things on my plate, that reading, if fit in to the schedule, should be a very enjoyable thing. I should be able to absolutely enjoy every minute of it, and if I'm suffering my way through a book; well, then what's the point in the first place of reading it? I don't think I've gone back and re-read books too often. But perhaps I'll give it a try. Might be a nice change of pace, eh?