Basically it is like doing accelerated subjects except everyone in my school does it! But that isn't the best way to explain it exactly
Just to put it into perspective, I will show you what my timeline was, with myself being in year 10 in 2015, year 11 in 2016 and now year 12 in 2017.
The subjects I have taken for preliminary overall were:
Advanced English, Extension 1 English, General 2 Maths, Society and Culture, Legal Studies, PDHPE and Business StudiesThe subjects I have taken for HSC overall were:
Advanced English, Extension 1 English, Extension 2 English, General 2 Maths, Society and Culture, Legal Studies, and PDHPE
Week 6, Term 4, 2015: I begun the preliminary course for Advanced English, Extension 1 English, General 2 Maths and Society and Culture
Week 10, Term 1, 2016: I completed the preliminary course for the above subjects
Week 1, Term 2 2016: I begun the HSC courses for the above subjects
Term 4, 2016: I completed and sat the exams for the above subjects
Then from October 28 to Week 6, Term 4 of 2016 I got to have a big holiday until I was required to be back at school for the next lot aka the best time of my LIFE
Week 6, Term 4, 2016: I begun the
preliminary course for PDHPE, Legal Studies, Business Studies (I also begun the HSC course for Extension 1 and 2 English)***
Week 10, Term 1, 2016: I completed the preliminary course for the above subjects
Week 1, Term 2 2016: I begun the HSC courses for the PDHPE and Legal Studies (dropped Business Studies)
Term 4, 2016: I will complete and sit the exams for the above subjects
***note: my school runs extension subjects like normal schools do
Basically if I went to a school that does the HSC normally, I would have done all the preliminary courses in year 11, and HSC in year 12. But, my school does the compacted curriculum format to reduce the stress as we have less subjects to focus on (3 subjects, unless you drop one then its only 2, or it can be 4-5 if you do extension subjects). The disadvantages come that it is SOOOO fast paced as with the little amount of subjects, it means you are doing them multiple periods a day, every day. So for someone with three subjects at my school, there was about 15 periods a fortnight of each subject, and one free period a fortnight. This of course was different depending on if you dropped a subject (aka SOOO MANY FREES) or did extension subjects (ext maths runs before school, and ext english runs after)
Hope this makes sense, feel free to ask any more questions!