Every time I exercise, I don't have muscle aches.
It is possible that after a period of training, the muscles adapt to the content and intensity of training, the growth slows down, and the strength can no longer grow. This is because it is impossible to practice active muscles and cooperative muscles in every movement like the bucket principle. Only when the active muscles and the cooperative muscles are in place can the strength grow steadily and the possibility of injury is small. So when you feel that your growth is slowing down, you can change your movements, weight and number of groups to stimulate your muscles again. To put it bluntly, muscle growth is a process of not adapting to it. Once you get used to it, you need a new way to stimulate muscle growth.