I recall, I hope correctly, that Karin Cadwell cited studies that showed around the world, babies suckled the same amount of time, regardless of whether they were on a q 3 hr or q 4 hr schedule or nursed prn or ad lib (including the African tribe that nurses 2-3 minutes out of every 12). For some reason the numbers that stick in my brain are 248 - 251 minutes per day.
Chanita, San Francisco