It's not about how much time on breast, but how much time baby is really eating. See if baby is engaging in sucking or just nibbling with little movement of lips. Hear if baby is swallowing. Try wake him or her up if he or she fall asleep during feeding. Compress your breast when you think the milk flow is slow (slow milk flow causes baby to sleep on breast). Finish one side before starting the other side. Feed until he or she is not interested in your breast.
Remove all him clothing and your clothing when feeding. More skin contact makes baby feel safer. Turn on a heater if your house is too cold.
Sometimes you can tickle his hands, feet, neck, he will continue to suck. When no more response, take him off from the breast. Wake him up continue to feed on the same side, compress you breast for more milk flow, unless you think there's not much milk coming out. Usually you can wait a bit because you may have second letdown and milk will come again.
People suggest continue to feed the pain side if possible, unless it's too pain for you. If you don't direct feed, express the milk out to feed after you finish direct feeding the least pain side.