I've been doing 5-6 hours a day average... and some days I do better and actually clock up 7-8. It gets tiring, and it gets on your nerves... but seriously, I'd do anything just for that feeling of confidence that I have before and after an exam...
I haven't really been doing past papers that much. I look at past questions, and construct notes from those that LOOK like essays, but as for little 40 minute/1 hour periods in which I just write... well, I'm a good studier. I know I could cram those in this week.
It's true what everyone's saying about how subjects matter. I have 11 units and 5 of them have the majority of the marks all done already (Music, Visual Arts, Extension 2... although the first two still have theory exams coming up)... which is good because I get to focus on the rest of my subjects, especially English. All this time I've been freaking out about people saying they're doing 10 hours a day... then I realised that I didn't really have that much to study for anyway (which doesn't mean there's little AT ALL. There's plenty, just not as plenty as other people)... and besides they're all humanities-based, which means that my mind is just on one track, content-wise.
The good thing, too, is that all my exams are spread apart quite well. I could focus on English this whole week (but do a little of other subjects as well) because aside from my Music Aural Exam (which is very good to study for), that's all I have for next week, then an 8-day break. So yeah, I reckon I'm doing pretty alright...