My bubs feeds 3 hourly at night, she is 4 months old and has done since birth. I really have to say I think that we are both blessed to be getting 3 hours between feeds at such a young age. A humans digestive window is 3 hourly even as adults. So I can't imagine a 6 week old purely on liquid going any longer. I certainly wouldn't want to wait if I was hungry and it isn't fair to make a little baby that's totally dependent do so either.