I've noticed that osmosis is one of my most effective study strategies, if not most reliable. Just as when I ran a residential painting crew during, and then after, my time as an undergrad, I've noticed that by simply running through the motions of what you think you are supposed to be doing can pay dividends. I remember telling guys on my crew during frustrating days when not a lot seemed to be being accomplished that when all else failed, if they were applying paint to the surface that was a good thing. What that meant was that even if they didn't have the best technique or work ethic, if the paint was simply being applied, the job was, in fact, moving toward completioon.
I am seeing this principle in my studies for the gmat, if I simply read over the problems, even on days I'm off a bit and not absorbing enough, by simple osmosis I have to be learning something. Simply by reading the text I learn, even if my brain isn't up to par. Long story short, keep your head in the book and eyes on the page. At the very least you're forming a good habit and it will pay off when accumulated over time.