The Maxis times vary depending on the parent and their baby's Hunger, Social and Comfort motives - ranging from 3 to 4 hours.
This mod shortens the amount of time the mother breastfeeds her baby. Slightly longer than feeding a baby a bottle, but not as long as the original amount of Maxis time it would take to breastfeed a baby. I was under the impression that the time spent breastfeeding a baby ranges from an hour to just under 2 hours, depending on the Hunger, Social and Comfort motives for the parent and their baby. I've been testing this particular mod for over a month to get consistent results.