At first look i didnt 'study' that much for my exams either. I probably did 4 hours for two days before hand for eah subject. In all honesty i did not study(as in sit down and actually study) that much throughout the year. But if you had a close look i had a pretty consistent effort else where which inadvertantly resulted in studying, i ran lectures at my school in most subjects(so i had to prepare notes and understand the content, which i highly recommend doing by the way, teaching others really consolidates your own knowledge), i crammed before sacs and i did some of the homework. If you take a close look, you may realise that you actually did a fair amount of work. A score in the high 90's requires some work, the knowledge required does not just pop into your head.