I have mixed feelings about this. It all really boils down to what strategy works best for you. Some students read the entire passage, others use search and destroy, etc. I was at a borders a few months ago and picked up an Exam Krackers MCAT verbal reasoning book just for strategy purposes and practice. I got about halfway through it and thought it was a waste of time. I personally feel like S&D is a good strategy for me, so I have been using that. Play around with the different options out there and see what works best for you (this is where CDAT RC comes in handy).