That's where the discussion comes in. With an instructor to moderate and a class working together who will overall have grasped it. Those who didn't pick it up reading learn by doing.
But personally, I don't like the idea of kids doing schoolwork outside school hours. I went to a trade-school college and we would do trimesters with 9 weeks for a single class. Spent the whole day just in that class, six hours. First half learning theory then putting it into practice in the second half. By nine weeks, you'd know that subject pretty well. But that was complicated stuff, and honestly, probably didn't even require 9 weeks. But it's a good starting model. Fully immerse kids in a subject for weeks where they don't have to mix in other subjects to muddy their forming brains. Homework won't be needed and they'll have a much better grasp on the subject at the end. You could do 6 classes for 6 weeks each a school year.
And I feel like early education kind of already does this. They typically will focus on a subject for weeks instead of trying to fit in 5 a day. It's just the upper levels we've decided to shuffle kids around multiple times a day.