I studied chemistry first and the most often because I took it freshman year and forgot most of it. Then I went to Biology, and then Organic since I took those sophomore year and they were still relatively fresh. Physics I studied last and spent the least time on because I was taking it my junior year, in time for the april test, the one that just passed. Everytime I finished a section though, I would review the other sections I studied right after it. After a while this didnt take much time because everything became more familiar and I could just concentrate on my weak points from each section.