Nothing else seems to matter. This is the essence of progressive resistance training . Now keep in mind that everyone responds to training differently. Virtually all of these differences are the result of genetic factors. Some people are genetically programmed to develop large muscles.
Some people have very good leverage for some movements.
And, some people are able to recruit a high percentage of muscle fibers and are often far stronger than they look. Knowing how much genetics influence your results is liberating. You can't change your genetics, so just go out and see what you can do. There's no magical routine. Just training longer or more frequently won't make any difference either.