This reminds me of a topic that comes up a lot at my house: late homework.
What should teachers do about late homework? Should you get a zero if you don't turn it in? Should you get 50% off for anything late? Should there be a limit on how late it can be?
If a student turns in 10 missing assignment in the last week of the semester, then gets a 96% on the semester exam, what grade do they deserve?
What is the point of a grade anyway? There are so many different meanings built into a grade. A grade can teach discipline and responsibility. It can teach respect. It can teach cheating. It can teach to do just enough to scrape by. It can teach that the important thing is to be higher than others. It can represent competency in a subject. It can represent value to the income of the football team.
Education is about so many things that it's hard to have a useful blanket discussion.
The correct approach depends upon the intention. If you are trying to improve people's understanding, you take one approach. If you are trying to vet competency for potential employers, you take a different approach. If you are trying to build a minimum base on which society can be anchored, you take yet another approach.