Every baby is different.
My baby who prefers sleeping to eating is actually on a 3-4 hour interval and has been like that since birth. Even now when she has started solids, she's still on the same schedule. I cannot feed on demand as she will sleep for over 4 hours and not wake up even though she's hungry.
I also dont't bother about the quantity as 1) she's doing 100% latch on and 2) baby needs to learn how to tell when they are full and not stuff themselves silly - it is their way of regulating themselves. If she is not crying after a feed or doesn't want more, then she has had enough.