Building muscle relies on a combination of reps, load, and tempo, with each playing a unique role depending on the individual's experience level. For beginners, focusing on load and reps is crucial, while tempo becomes increasingly important for advanced lifters. Progressive overload can be achieved through various methods, such as increasing weight, reps, or manipulating tempo to enhance technique and mechanics. Ultimately, the best approach varies from person to person, emphasizing the need for personalized training strategies.