I never really understood why book publishers need nine to twelve months to get a book into print. They act as though it's such a careful and meticulous process that anything less would result in an inferior product. The idea is that by the time the book finally does see the light of day it has been proofed, and checked and is ready for prime time.
So I was quite surprised when I was proofing the scan of my 1989 novel, Gold, so that I can reissue it when Penguin gets around to reverting the rights to me, to find that there were more typos in the original version that needed correcting than there were from the scanning. On the one hand, scanning has clearly improved, and the service I used, Blue Leaf, must have up-to-date equipment. But the fact that there were more than a dozen typos in the original was really kind of shocking. I don't know whether my book got a particularly sloppy copy edit and proofing (and of course I got a copy of the uncorrected proof myself for review) or whether it is easier in fact to spot errors on the screen because of the wiggly red lines under misspelled words.
In any case, I'd like to think there are fewer errors than that in the novel I self-published last month, The Grand Mirage, which got two proofings from two separate pairs of eyes and still got out in a month.