ok my turn for case studies. as bullshit as it is your cohort will have a great influence on your SS

take my two highest raw scores, English and Biology
for Biology i was A+ A A+, will the mid-year A being 1.5 marks off A+, and end of year being mid-high (full score on M.C.) these scores resulted in me getting 40. 3/4 of my cohort had midyear results of C+, a B+ and two As (one of which being mine). had my cohort been stronger, my SS should have been more like the ~42 i estimated
for English i was B+ A A+ in again a weak cohort, of which my 38 was equal highest with another girl. (very disappointed)
for me to have received 38 with only a single A+ it mustve been (as ive been told) a mid-high.
so to summerise, to get 40+ SS your own effort is unfortunately not the only influence, but your cohort can cost 1-2 SS if it is not at your level.