There's no "right" way to study, how long to study, etc.
People told me to drop and I was 'too far behind' when I hadn't written my MW during the summer holidays. I eventually wrote it (with no repercussions) during the first few weeks of term 2.
A different person told me that doing 3...
Yes and no. Subjects I was naturally good at (English, 2u) I did almost no work for. Subjects I sucked at (Chemistry, MX1) I would say I did 1-2 hours a day excluding week ends for, if you averaged it out over the year?
In the end the subjects I was naturally good at ended up saving my ATAR...