I would have to disagree! One sac doesn't determine your study score, and even if you didn't perform to your expectations in one, doesn't mean you will keep performing similarly (you have the power to change your average!). You can still afford to bludge one sac (not all of them!) and still get a 40+.
Absolutely agree with whys here!
The SAC's main purpose is just to get the order of the ranking right and just because you do badly in one SAC doesn't mean the end of the world. I had a friend that failed 2 Physics SACs and still got a 42+ study score. In the end, it really boils down to exam performance (because that's how your SACs are moderated) and how well your cohort goes. Since each school is different, it's definitely not right to compare just based off percentages because some cohorts (like selective schools) may have harder SACs to order people for rankings rather than a weak cohort which has easier SACs.
Just remember that the SACs are there to see what gaps you have in your knowledge as well as how you can improve in the future. It's a learning experience and so long as you are improving each day you will be alright. Learn from your mistakes (because we are all human
) and whatever you do, do not give up. Be resilient and as weird as this sounds, enjoy the challenge! You will be absolutely fine and nothing is set in stone till the exam.