Actually, cooking requires skill. Generally, cooked meat products should be tender, smooth and juicy, and low fire should be used.
Because if fire is used, the surface of meat products will instantly become ripe and tight when it encounters high temperature, which is not conducive to the penetration of heat into the meat. It is also because of osmotic pressure that the water in meat products will be squeezed out of the soup. If there is not enough time, the meat will have hair and firewood, which is what you said.
If you use a small fire, you will keep the noodle soup in the pot open after boiling, that is, the water temperature is 85-95, but it is easier to stew. Because this kind of heat slowly enters the meat, constrained by the principle of thermal expansion and contraction, the surface muscle tissue will open, and heat and moisture will penetrate into the meat, so it is easier to ripen at low temperature.