Personally I did 15 practice exams and in the holidays re-did all my notes (however take into consideration that I did Psychology in year 11 so I could afford to have this much time). It is also very important to get feedback from these practice exams, as just doing it for the sake of it will not necessarily boost your study score.
What I would recommend is while doing these practice exams, when you're not comfortable with a topic, just put a star next to it, and add it onto a list of "topics you're not comfortable with" after you complete it. Or what my teacher recommended is highlighting the practice exams based on AOS (e.g., highlight AOS2U3 with blue) to see what topics you need help with. Then study these the most!!
