To pump for 15 mins on 3 hourly schedule or to pump for 30 mins but 4 hourly?

Most experts agree that it is best to pump at least 15 minutes, and to avoid going much longer than 20 minutes. It is also encouraged tp pump about five minutes after the milk stops flowing. By doing so, a breastfeeding mommy will elicit another letdown, and at the very least will maintain production as well as encouraging an increase in supply.