Yep I asked my examiner teacher today and said that you do not need to do 1,200 words to get a 10/10. She also said that it is rare to get a 10/10 and that many of the 10/10's are chosen by a computer system from people who are originally given 9/10 to fill in the required amount of 10/10 that need to be given out.
That sounds ridiculous - according to some VCAA markers, there are often essays that are realistically more like 14/10, and the kids who do well in SACs that I know of often end up getting 10s for one or two essays on the exams, so it doesn't seem randomised. Surely there's no way in hell they do something as bizarre as what you've described...
Agreed on not needing necessarily 1200 words, but 1000+ is still recommended. Note that 1000+ does not mean having to reach a hefty number like 1200 either...