How much of a 4-year-old's time at home should be directed by an adult, and how much should be free play?

I say free play all day. School is for teaching, home is for playing. Children spend so much time & so many years in a school environment, their home environment should be just the opposite. I wouldn't have him sitting at a table/desk doing work. It would just be all fun in play. Of course you can mention colors & numbers, etc with play, but I would not teach as a teacher per say.