Children in the upper years of the Ambleside schools in Charlotte's day spent more time on lessons than the elementary-aged children. The bulk of lessons were finished in the morning hours before lunch, but they continued awhile in the afternoons reading some literature, going on nature walks, doing handicrafts and practicing an instrument. They also went to school on Saturday mornings, by the way. Plus, they were learning more languages than we do. Don't faint now, but 3 and 4 languages were studied at 12 and 13 years of age, Europe being a multilingual area of many nations. My children spent most of their childhood in Asia and so learned a foreign language while young, but most folks don't have such opportunities. So you will probably be working on just one or two languages.
My 7th year students work on lessons for approximately 4 hours every
morning and have an hour of free reading right after lunch and chores.
Many subjects get accomplished because I trained the kids with timers
when they were younger to move from one subject right onto the next with
out delay. I also keep the lessons short. They know that I have given
them enough time to get it done in the morning hours, but if they waste
time, they have to use their afternoon quiet time to finish the day's
work. Otherwise, no heavy schoolwork is scheduled in the afternoons.
Math and Science have to be finished in the morning while their brains
are fresh. The rest of the afternoon they are free to follow their own
interests until I snag them for an hour of outside work in the cool
evenings on our farm.
They are in charge of their schedules. I have a simple schedule template that I use for each student for all twelve years. You can learn more about the Daily Checklist here.