Regarding the "due date" excuses

Two common policies at my school:

1. For recurring assignments/quizzes: your lowest one or two marks don't count, so you can afford to miss/fail a few for whatever medium-good reason you choose. Thus you decide what is "good enough" based on your own expectation.

2. If you want some grace time for an assignment, your excuse better cover the whole working period of the assignment. If you leave something to the last day, and then get sick, it's your own damn fault, that is to say: for assignments emergency excuses are invalid.

My interpretation it perhaps uninformed because I never asked for any grace about deadlines or marking during university.