For us it was 7:20 high school, 8:20 elementary, 9:20 middle school. Reason was using the same busses and high schoolers were more likely to need time after school for work or sports/band/after school groups.
In practice it meant that I could pull 40 hour work weeks starting at 16, then by 18 be working some nights till 1-3am and getting up for school in the morning. Stupid decisions were made.
They made laws to further limit the hours kids could work after to try to make healthier opportunities for kids. Unfortunately a certain governor is trying to carve those laws up now. (Desantis)