Each book depends on your purpose. I will gladly still spend 3 to 4 hours with a good novel (beats 18). On the weekend I activated 5 books in an hour. (I had a witness and we discussed the books afterwards).
I don't see much point in trying to guess how much time you might get your reading down to. Look for quality in the time you spend with a book. Don't set yourself up for disappointment. Just expect to improve on your own times and learn to get your Reading town in the time you have available with the comprehension level, you need.
AlexK
