Somewhere in the middle. Children are 7, 4, 3 and 1.
We use some workbooks for a few hours a day (not all at the same time, though) because I've found that they like to have something tangible to show Daddy when he comes home. It's also a useful thing to be able to show grandparents and others who have a certain preconception about what education is.
But essentially the workbook stuff is primed for learning to read, write and discover maths. I figure if they have the basics down, that opens up the world for them so they can explore, which I'm already seeing happening.
Other than that formality, they spend the day exploring, reading, investigating the world around them and so on. At the moment, this tends to involve 'making a den' that ties in to whatever we've been looking at recently. This past month it's been 'the Celts', so the den has been a Celtic fort
I would imagine, as they get a bit older, it will get a bit more formal, but I just had the biggest smile on my face the other day when my eldest was sitting reading the her younger sisters, reading words like 'phlegm' and 'feign' confidently and with expression, and I realized I've actually acheived something, because I've taught my daughter to read. Sorry, nothing to do with the topic, I just got carried away there.
So, anyway, yes, in the middle for us.