We can change/ redesign the content of school curriculum, or change the way for students to learn. It's not necessary for students to learn only IN SCHOOL. Think about flipped education, some lecture can be taught by mediums like video.
First, students don't always make good use of their time, if they can stay at school, at least teachers can make sure that they are not doing things not related to the courses. Second, if students go home too early, their parents won't be at home at the time, so they can't be with family either.
Having more free time to explore themselves DOES NOT MEAN WE NEED TO THROW THE GUIDES FROM TEACHERS AWAY. These guides could be covered in school time, and students will have more vacancy to make more "trial and error"
Over length school hour cause Not Enough Time To Sleep, Having Social Life outside of school, exploring personal ability. We should postpone the time students going to school, or shift the ending time of school earlier.
[Too much curriculum content] Teaching so much content in short amount of time is unnecessary! We may need to change the content of our education, since the curriculum now acts like an encyclopedia, it requires students to learn ANYTHING academic-oriented way.
[Traffic Problem] If students go to school/ come home from school later/ earlier than current time, their parents won't be able to catch them on time, since communicating time a shifted. (inconvenient for those who live far away)
[DRTS] However, there's already a method which can solve this problem: Demand Responsive Transportation System, DRTS, which uses flexible routes and small vehicles to send passengers to transit stations for further transfer.