I think both are important though really. I find that doing just practice exams - although usually sufficient - makes you far less adaptable to new-style questions than if you just studied the concepts for what they are, as opposed to basically studying for specific questions. People get in the rhythm of seeing VCAA put particular questions in the same year and get in the habit of mastering full mark answers for these, but the problem is that when they don't, they freak out and have no idea where to start. For example, in the BM exam that just passed, everyone thought a particular question was coming up but it didn't, but since they already had their answer for the 10 mark question memorised, they felt obliged to stick with it even though some claim it wasn't relevant. Not too sure about the specifics but I'm sure you get the point. Instead, learning the concepts allows you to do a question off a clean slate without any preconceptions. I believe this is what marks the difference between those who get low 40s and high 40s because those in the low 40s generally know the entire course and have done heaps of practice exams, but inevitably screw up the strange question that VCAA inevitably manages to fit in every year. Especially for bio, I would recommend notes. There is just SO much to cover that there's some stuff that VCAA's never tested before, but could easily manage to test in the coming exams. Doing notes ensures you cover every part of the study design.