What we think really doesn’t matter. Personally, I think 3 hours of formal learning is on target for 10, but way too much for 6. I can understand a formal art curriculum for upper elementary, but (IMO) it would be wasted on 6-7, maybe 8.
I homeschooled preschool through high school. This was the daily breakdown for time:
Preschooler did workbooks whenever he wanted, which usually amounted to starting with the older kids and moving on to something else 15-30 minutes later. For the rest of the “school day,” he had independent activities that built early literacy, numeracy and fine motor skills, and he had full choice of what he was doing and when. Sometimes he decided to do more workbook pages later.
Kinder: Phonics: 5, Sight words: 5, Reading comprehension: 10, Writing (and drawing a picture): 10, Handwriting: 5, Grammar: 5, Spelling: 5, Vocabulary: 5, Math: 10, Science: 5-10, Social studies: 5-10; total: 70-80 minutes
Second: Sight words: 5, Reading comprehension: 15, Writing: 15, Handwriting: 5, Grammar: 5, Spelling: 5, Vocabulary: 5, Math: 15, Science: 10-15, Social studies: 10-15; Total: 90-100 minutes
Third: Reading: 15-20, Writing: 15, Handwriting: 5, Grammar: 5, Spelling: 5, Vocabulary: 5, Word study: 5, Math: 15, Science: 15, Social studies: 15; Total: 100-105 minutes
Fifth: Literature: 20-30, Writing: 20-30, Handwriting: 5, Grammar: 5, Spelling: 5, Vocabulary: 5-10, Word study: 5-10, Math: 20-30, Science: 20-30, Geography (physical/political): 5-10, History: 10-20, Civics/Government: 5-10; Total: 125-195 minutes
Seventh: Literature: 30-40, Writing: 30-40, Handwriting: 5, Grammar: 10, Spelling: 10, Vocabulary: 10, Word study: 10, Math: 30-40, Science: 10-20, Science lab: 10-20, Geography (physical/political): 10, History: 20-30, Civics/Government: 10; Total: 195-255 minutes
Ninth: Literature: 45-60, Writing: 30-45, Handwriting: 15, Grammar: 15, Spelling: 15, Vocabulary: 15, Word study: 15, Math: 45-60, Science: 15-30, Science lab: 15-30, Geography (physical/political): 15, History: 30-45, Civics/Government: 15; Total: 75 minutes never changed, 3-4.5 hours for the variable subjects
Foreign language was as a group: preschool and kinder 5 minutes, second through fifth: 10 minutes, seventh and ninth: 20 minutes
Music and art was self-paced starting in fifth, incorporated into the above subjects (and time) through third. Everyone had a lesson for an instrument of their choice starting at 4/5, and practice was a minimum of 3 times per practice piece.
We had a homeschool PE class on a (sixth) day during which we did no formal learning. Each child also was responsible for playing/physical activity on their own.
All the kids had chores to teach life skills: gardening, housekeeping, childcare for relatives, car maintenance, cooking, etc. The goal was to have kids capable of doing anything required by the time they reached ninth grade. They also got themselves a job outside the house (as age-appropriate). The high schooler was studying the driving manual and observing the driver in preparation for taking the written test and getting a permit (no driver’s ed required, just tracking hours with the permit).
With that said, even the ninth grader had plenty of time to do other things. I can understand wanting to do a foreign language and art, but this is one of the reasons that I prefer setting my own hours.