^^I disagree in part.
I personally feel doing practice questions is excellent for the purpose of improving essay technique and to refine on-the-spot-writing technique. It's not always about knowing what they ask/knowing what to answer, it's about knowing your stuff and being able to write everything you know about it off the top of your head - no preparation! It is pretty darn easy to make an educated guess as to what the question will be - for AOS, the generic question will *always* be "How is the notion of Journeys reflected in your prescribed and related texts?". I know it, now you know it, and by September, when everyone starts cramming, they'll also realise how similar past questions are.
I strongly advise against coming in with any prepared paragraphs to "mould" to the question - which is essentially rote-learning, not good for the HSC and utter suicide for University. Instead, know your points. Know your stuff. Be familiar with HAND-WRITING - yes, unless you have special provisions you will NOT get to type out your essays in the HSC - essays, and be familiar with the sight of a new essay question at the top of your page.
This is why doing practice essays is good - and the more, the better. It'll give you a feel of how to interpret and answer questions well OFF THE TOP OF YOUR HEAD, as opposed to practicing how to mould your "perfect essay" into the "perfect HSC response".
*rant over*