An article noted that some disagree that shorter school days are to blame for U.S. students falling behind other nations, that in countries such as South Korea, Finland and Japan students spend less time in school than they do in the United States.
I would also suggest that these cultures value education; parents and other family members participate in the process. They don't just blame the teachers if a child struggles. It's the family's responsibility as well.
We talk a pretty good game about the value of education, but many parents consider their child's education a teacher's problem after all, they send them to school! but don't feel a need to take part in the educational process.