I've found all of my textbooks to be a useless waste of paper. I've started going back through my Calculus book, but I haven't made it past the diagnostics test yet, I've just procrastinated it, solving the occasional problem. I'd benefit most by buying the pages as I use them lol, what kind of person makes it all the way through a thousand pages of mathematics!?! Some books from other topics might be a little more digestible, but I don't want to buy another maths book until I get through the first one
add: Though they do say that they should be used as references to back up the lecture slides, still, it's pretty frustrating knowing that ~4000 pages of information is going to waste every year.