It is best not to suck milk for more than 15 minutes on one side of the breast. During breastfeeding, the child may only eat the milk from one breast, but not the other, so the milk must be sucked out at this time, otherwise the milk may block the ducts of the breast and form hard knots in the breast, or even form mastitis or breast abscess. When you have finished breastfeeding, you should use a breast pump to empty your breasts in this case. It is not determined by how long the breast pump is used, but by the amount of breast fat, as long as the breast is soft. So some people have more milk fat content to suck for a longer time, and some people will have less milk content to suck for a shorter time. Just make the opposite breast reach the same state so that it will not be prone to breast hardness and mastitis.