I'm homeschooling one 8 year old second grader. We use a method similar to the workbox idea. She has 12 assignments/tasks each day that we do when we do our "formal" school (usually 4 days a week). The only structure is that she must do the things in the boxes before she plays or does other things. She chooses the order and she chooses how long they take (LOL). I make sure that we do reading (her reading aloud, me reading to her, reading together, phonics workbooks, etc), math, writing and spelling every day. The other 8 assignments vary. As soon as she is done, she is free to spend the day playing, watching educational shows, doing art projects, etc.
This is working really well for us. It took a few months to find something that felt right and worked well. This allows her to be self-motivated and feel like she has some control.
I just think it's SO individual.