Yeah I did. I was part of an accelarated program. The minimum amount of 1/2 we had to do was 3, max 4. Most of my class actually did 4.
Wait, this is assuming you mean Unit 1/2 subjects not 3/4's. But yeah. We had to do English, Methods and History, but we could also chose a fourth subject of biology or busman.
As long as you do the work, and put a decent amount of effort into you should be fine. I cant really say I did that, but I think I came out alright anyway and I did History in Year 11 (at a different school) as a result, and had I stayed at that school I would have done English or Methods as well.
And I definitely recommend you do a 3/4 in Year 11, it saves you the stress from needing to ace all your Year 12 subjects.
What subjects have you chosen?? And do you mean Unit 1&2 subjects or Unit 3&4's??