This might be a bit contentious, but the point is, study smarter. Do what you actually need to do, and don't do stuff which is inefficient. Half the homework you get in school is a waste of time; I only did what I knew was actually useful. If I already understood something and got homework on it, I'd either not do it if I didn't have to hand it in, or just rush it and have something half-assed to hand in for the sake of passing and not pissing my teachers off (very important in terms of SAC marks and for other reasons). If it is useful, know how much of it actually is. Never do full maths exercises, and you'll rarely need to do even the amount set out by your teachers. Doing that extra page of differentiating linear equations is unlikely going to make you better at it if you got the last 10 correct as is. What you do need to do is the amount which lets you understand the concepts. The repetitive format in which maths textbooks are set out doesn't really help reinforce this - often people get like question a and b wrong and then look at the answers, learn the process involved, and then just copy that process and apply it to c onwards and get the rest correct. If you're not sure where you stand, this is where tutors are useful since they should be able to stress the limits of your knowledge out of you with an appropriate question.
Also as an extension of the above, with so many subjects, I would recommend knowing early on what your bottom 2 will be, and allocating your time accordingly. You're only reaping 10% of your effort out of them, so it's better focusing your efforts on what you think will be your top 4. While I'm not advocating utterly flunking your bottom 2 as they can be good to fall back on, this is good to do if you're confident of what will be your top 4.
To clarify the above though, this is the most important rule of time management in VCE really; the benefits gained with regards to study score over time is exponentially decreasing. Likewise, and perhaps a more clear way to say it, as you aim for a higher study score in a subject, the time required to achieve it increases exponentially. For example, to achieve a 40, a person might only need to do 5 practice exams; a 45, perhaps 20; a 50, this might rocket up to 50 practice exams. Because of this, to maximise your end aggregate, try to balance out the subjects in your top 4, while allocating a little to your presumed bottom 2 because to get them to a half decent level doesn't take that long in comparison. Of course, this more applies if you're an all-rounder, and your own strengths need to be taken into account when determining how to allocate your time.
There's other factors involved too though of course. Basic rule I use is that during the year, learn concepts. Concepts can be difficult to grasp and knowing which concepts you don't get during the year means you've got plenty of time to access resources so that you do. On the other hand, before the exam, rote learn the stuff you have to, because if you learn it any earlier, chances are you'll have to rote learn it again just before the exam and there won't be much difference compared to if you had just crammed it anyway. This means for rote learning heavy subjects (e.g. BM), cramming before the exam is likely to be most time efficient. Concept heavy subjects like Math take more consistent work, but only just enough so that you understand the concepts; repetition of simple applications of concepts don't make you any better at them - you've got to stress your knowledge with analysis questions and whatnot. As I said at the start, a heap of what I've said here is likely to be contentious, but this is what I found works best for me.