I am talking about the PISA survey. France is not doing better than US or Norway. Actually if I remember correctly. France has higher educational inequality than the US.
Sure I can do that. Let's say 100 is full learning speed. And this is how much you learn per hour on average.
0H: 100
10H: 90
20H: 80
30H: 70
40H: 60
50H: 50
60H: 40
70H: 30
I will assume an average french student does 5 hours of homework each week. Although, I haven't taken it into account, but homework also helps students become more independent. Your boss or teacher are not always going to be around.
France is nowhere close to the plateau where reducing study time will improve performance. They are on the left side of the curve.