It varies from year to year I guess. It depends somewhat on the strength of your cohort, and also how everyone else does in the exam - after completing VCE I'm STILL not 100% sure how that confusing system works, but I'm guessing if everyone does well in the exam it'd be a lot harder to get a 40 than if it was a harder exam and you did pretty good on it - maybe not excellent, but good - and a lot of people struggled. But yeah, just because you mess up in a few sacs doesn't mean you can't get over a 40. In english I managed to get a score of 47, and I think the lowest mark I got on a sac was 93% - the rest were generally 97%, 98% and 100%.
However, in lit, I received a raw 40 as my study score, and my sac results through the year really weren't that impressive - I think I even got 70% on one sac, and most of my other sacs ranged between 80-85%. I think I only got one 90% the whole year. So yeah, in that case, the exam mattered a lot more, and my sac marks were scaled up because of it. So I'm guessing it's possible to drop below an A+ in english and still get in the 40s, as long as you do well on the exam.