I lived in a rural area during this time in my life. School started at 7:30am, the school bus picked us up at 6:30am, which meant I had to be up at 5:30-6:00 to eat breakfast, shower and get ready for the day.
This meant a 9:30 bed-time.
This also meant that I got home by about 3:30-4:00 depending on traffic. An hour for dinner gave me 4.5 hours to study. Let's be honest, I also took an hour for free-time otherwise I wouldn't have any. So 3.5 hours to study every day.
In college at least, when you plan your schedule, you should plan 2-3 hours of study-time per week for every hour of class time. As you can see I really only had time to study 1 subject a day, maybe 2 if I didn't give myself free time by that standard.
The district my kids are in is even earlier, we're at a very high latitude, and on paper the reasoning is so that even in the darkest days of mid December the kindergartners travel time at the start and end of the day will be in sunlight.
The same bus that carries a high school kid between 6am and 7am carries a grade school kid from 8am to 9am (roughly). Its actually even more complicated because we stagger grade school, middle school, and high school, so there's a middle school run from 7am to 8am in between. Rather than three times as many buses and drivers each only working two hours a day, they all put in pretty much an 8 hour working day split shifts.
Unofficially its all about high school sports and away games travel time, also somewhat optimistically getting in a practice or maybe even a game/meet before a "normal-ish" dinner time.
