In the past 5 years, I've never completed any homework or have studied for any amount of time. Only the required assessment tasks and assignments that I have to do, I do.
In year 12 now, I'm actually putting in some effort. I just have notes and summaries for the cram subjects such as economics (Having notes on par with what you're up to in class and revision 15 mins a day keeps everything fresh.. At least for me). And do the homework and extra exercises from textbooks for maths and other subjects of the like.
I dont need 3 hours a day.. Those people that study like 3 hours or more a day are wasting their time.. Seriously.. They're either daydreaming about who to take to the end of year formal, or playing with their pen or half talking on MSN.