To put it simply, northerners bathe vigorously because people don't bathe every day. If you wash it every day, just rub it casually. Taking a bath in the north is a life attitude, a social way, a kind of leisure and laziness, and generally you don't go by yourself. When I was very young, I went to wash with my father. Father will order a pot of tea in it and brag to the regular customers inside until the tea is weak. After school, I went to take a shower with my classmates and friends and rubbed each other's backs. It's quite interesting, but I didn't wash it as long as adults when I was a child.