I lived in Japan as well. There is an hour in the morning for music or something and an hour or two for after school sports. The actual in class time wasn't that bad. Plus a lot of time spent socializing and hanging out. Some kids would be out till 8-9 before they came home. They weren't in class all day.
They do better because they have a culture that encourages it.
Normally I don't do this but I was curious. I RTFA and it seems that the studies were all about preventing pooling/jamming. It may be true that by creating disruptions one can reduce jamming but how does that affect the overall traffic flow. I would suspect in a perfect system each car abiding by the rules would have the greatest flow. What is hard to determine is that in the real world what would be the best.
Actually I don't think it really matters. Even if the study shows that driving 65 and leaving 5 second gaps can prevent 50% of traffic jams the social change necessary probably wouldn't happen.
Remember to say hello to your bank teller.