Funny, I was just wondering the same thing about my ds! He'll be eight weeks on Wednesday, and he's taking 5 oz every 2.5-3.5 hours (except at night). I think this is an awful lot of food for such a little guy but it seems to be what he wants. I may actually increase the amount to 6 oz because he's been sucking his bottles dry for the past two days.
As for getting him on a four-hour schedule, I am tempted to try but I think I may wait a while. I could never get Ben to go four hours in between bottles until he started taking solids, and I have a feeling that trying this with Matthew may be met with a LOT of resistance :lol:
In all seriousness, though, I have heard of a lot of kids who never get on a four hour schedule on formula, even though that's what they 're "supposed" to do. You could give it a try, and if it doesn't seem to be working out after a week or so then just go back to what you were doing, especially if it seems to be working fine. Once he starts taking solids this will probably change.
Good luck!