It is near impossible to maintain a schedule like that in any facet of life and actually benefit from it.
I just finished reading a book "Do Less, Be More" that discusses at length the effects and implications of overworking and the little benefit that is received.
Sweden had most recently put in place 6 hour working days, and employees found that they could do the same amount of work as 8 hour days, with less unproductive moments and have more time to pursue hobbies, family and self development.
What I'm trying to say is that there is no real use is increasing the hours you are studying, as hours do not equate to performance.
If you really knuckled down for 2-3 hours with 5-10 minute breaks in between for example, you would be able to achieve similar results to spending 10 hours. Even if you planned to be quality and productive the whole time, it would be near impossible to sustain that. During the 4 weeks of HSC exams, 6-10 hours is a time frame that most people would be working in.
Instead of trying to be constantly busy, pick out the activities where your energy will be used most efficiently, and that will have the greatest impact on your results and goals moving forward.
Best of luck.