First, please list out what you mean by 'do less work'. What is your definition of 'satisfactory' performance, aka C grade.
While civil servants are excluded from the employment act, but
MOM's definition of a 44h work week still serves as a useful guideline for all workers.
Also according to
MOM laws, no one should be working over 12h a day, or do over 72h of overtime each month (roughly 18h of overtime a week)
No one should be expected to work for free. Or, do be expected to do unpaid OT on a permanent basis.
For any law-abiding employer, 'satisfactory' work performance is assessed based on reasonable amount of workload that an ordinary human being can complete during their working hours.
Can sticking to 44h work week get an ordinary teacher a C grade?
Can working beyond 44h/week guarantee a C+ or better grade?
If yes, I rest my case.
If no, it means that something is seriously wrong with the system.
Everyone should have at least 25-30h of contact time (lessons, FT, CCA, CCE etc)
Assuming a typical load of 5 classes * 40 students, and minimally 1 piece of homework to be marked each week, and assuming consistent superhuman efficiency of 5min/piece of homework, it would still take more than 16h to to complete marking for each week. Just teaching and marking is enough to exceed the 44h work week.
Haven't factor in staff meeting, subject/level meetings, CCAs, lesson prep, committee work, paper setting, and other duties.
Can say no to all these?