Probably answered already, but the initial question about SAC rankings changing is kind of true. My Literature teacher said that if someone got a high mark who probably won't do that well overall, she would still give them a B, not the A they deserve for that SAC. But that's probably because in literature SACs are so different to what the exam task asks you to do so it's not a good indication of exam performance. Also, it is kind of fair in certain cases. If someone was an anomaly and did really well in one SAC, but their past sacs had been up and down and then their future SAC mark was dodgy, would you really want to award them such a good mark that would let them CLIMB UP THE RANKINGS, to a position where their exam performance could easily affect your scores as well? I.e, rank 1 or 2? She was doing it to protect the cohort I think, cause a few years ago our rank 1 got 38 and the scores were terrible.