If you hit high 5's or low 6's, you're actually destroying the subject, all you need to do is beat the average and scaling isn't an issue
people get cocky about the subject, don't study much for the HSC course, while most the exam is easy, those big chunk extended responses where you
do need to study is where alot of people fall down, my Year 11 IT exam, I got almost full marks for every single mark, i lost about 15% (I got 82%) in my 2 extended responses because I 'didnt communicate professionaly, and provide clear points'
Teacher said I had the idea, I just should of structured it better and used much more formal langage (one extended response was a letter), so If I had just a more mature vocabulary, and practise my structure reports it would of been easier
On top of that, the teachers said the HSC will be AS HARD as this exam that I did, so I recommend you don't bother with the menial stuff and focus on your ability to do an extended response properly.
To further validate my point go here
http://www.boardofstudies.nsw.edu.au/ebos/static/BDHSC_2004_12_16365.htm
Let me analyse this for you 3732 applicants, Band 6 is great, its achievable in this subject, but why do 1.01% get it?
Thats ~38 people in the STATE got band 6, band 5 is also very achievable 9.61% got it, thats about ~359 people
You remember that big curve graph that analyses scaling in subjects, remember how it has that spike in the middle as the 'most common mark' - well in this subject 72.63% of people fell between bands 3-4, so that 'spike' is in 3-4, so if you hit 5's, or 6s you really have nothing to worry about
Lets say I properly constructed my extended response in year 11, im looking at mid 90s, thats more or less a good mark
If you for some ungodly reason hit only 70s i recommend you do something about it, or drop it