I probs wouldn't memorise an essay because they could legitimately ask us to focus directly on one character, for example. They can be very specific. I'd rather remember about 3 different themes for each module, 2-3 quotes for each of those themes, and a bunch of techniques for those quotes so that you can analyse them. If you look at Example B in Section II of the HSC Sample that NESA released, they can give us a specific question that defeats the purpose of a pre-memorised essay. However, you could go ahead and memorise one and then get lucky if they give us a generic question.