Imagine telling someone learning the piano to switch instruments every six weeks. Or telling an entrepreneur to change businesses every six weeks. Or telling a writer to switch languages every six weeks. Nobody would recommend that. Because they understand that skill comes before mastery. The same is true in the gym. Every exercise has a learning curve. Before your muscles can get the most out of a movement, your nervous system has to learn it. The better you become at an exercise, the more stable you are. The more stable you are, the more force you can produce. The more force you can produce, the better the training stimulus. If you keep changing your program every six weeks, you never spend enough time beyond the learning phase. You keep paying the cost of learning. You never collect the returns of mastery. Change your program when you’ve outgrown it. Not because six weeks have passed.