It's interesting how different the quality of schooltime can be, and how perception of said time can differ for school kids as well. I was in a "full day" school starting from age 9 in a country where regular schools end at lunch time. Our school had the same curriculum to go through as every other, but lots more time to do it. The extra time was filled with dedicated self-learn time ( basically to do homework, but you have your classmates around to talk and help each other and can reach out to teachers if you really struggle with something) and elective extracurricular activities. It was mandatory, but you had free choice between all the offers. Teachers had to offer something, and usually offered their personal passion activities/hobbies. This led to these activities being the highlight of every kid's week, because there was enough variety to choose from to find something you liked. Kinda like club activities in US schools, but much less codified and without competitive objectives. Some examples are photography, pottery, soap box car building, school beautification ( we literally were allowed and encouraged to graffiti/mural the school walls :D ), gardening, natural science ( basically constantly doing fun physics and chemistry experiments without boring theory), electronics etc. . This was intentionally kept separate from sports or music, which also were partially elective: you had to do sports and music, and some basics were mandatory for all, but you could opt for specializations. All this semi-forced mingling served well to prevent the formation of strong clique boundaries, without inhibiting kids from pursuing their talents and passions.

All that had huge advantages. Kids from troubled families had a much easier time of keeping up with everyone else, as help from home was hardly necessary. Lunch was provided by the school. Wasn't stellar, wasn't horrible. But it was available to all students for free, and that can be very important to some as well. It took me a long time, often only after visiting school friends for the first time or even after schooltime was over entirely, to realize how crazy rich or poor some of my friends' families actually were, or what difficulties they sometimes faced at home and that there was a reason we never were invited to visit them. At school, it simply didn't matter to us. Sure, some wore more brand clothes than others, but nobody thought of using this as a measure of personal quality. Class cohesion also was usually strong. Sure, kids still were assholes and bullies like everywhere else, but it usually got solved internally quickly, because it was harder to keep it up for full days with plenty of "forced" social time, and you ended up being more confronted with the damage and hurt you caused. And in really bad cases the proximity to school made it much easier for teachers to pick up on any developments in their students and classes and react quickly. There also were some mandatory "social skill" classes to teach everyone basic conflict solving and mediating. It was only one or two sessions per year, but I think it actually helped, even if we kids usually scoffed at it at the time. It was very clear the school philosophy was not to push through a curriculum, but to use the extra time to help explore and form personalities that later will hopefully enmesh well in society. And yes, our school had a bit more teaching personnel than other schools to fill all the time slots and extra activities, but we still had 25-35 students per class, it was not some utopian dream.

We kids loved the full day spent at school as well. No homework, and what's better than spending the entire day with your friends? The school was far from my home, so I left the house at 6:30 and usually got back around 18:00, with about 40min of train commute plus 30min of walking (one way). Only Friday ended at lunch. Still never felt that I was lacking "me" time.

Tl;Dr : It matters a lot how the time at school is used.