Charles Spurgeon, in his Lectures To My Students, notes that "little learning and much pride come of hasty reading."
He goes on to note that one should read and re-read the books you have, until you have mastered them. One book thoroughly mastered is better than twenty books merely skimmed.
Sometimes I tell someone about a great book, and I can't even remember what I learned from it, just some general thoughts. Was it really good, or am I really dumb?
Granted, we should read more than 1 book, and we shouldn't expect to remember everything we read. But we should master something - starting with the Bible. Re-reading brings life.
If you've seen The Book of Eli, you get a new appreciation for regular Bible reading. I'm contemplating reading the same book of the Bible for a year, to try and bring more understanding of just a small bit of life. At least then I'll remember what I haven't mastered.