if extra workload translates to extra pay, i am sure it would not be the case.

Unlike tuition in which the more students you teach, the more pay you have; in MOE schools, you can be doing more work, but if no one recognises it as making an impact, then your pay may even be less than expected. Does anyone even care how much marking you do for students or that you even prepare your own resources cause no one in the dept bothers to update the resources after donkey years?