The same is true for a lot of performance stuff, like racing, or basketball. Basketball coach Phil Jackson writes that when you move quickly, do not hurry or rush. Don’t go so fast that you start making mistakes. In racing, “do easy” is even more applicable. Overdriving the car doesn’t find you much more lap time. The fastest, most consistent drivers are smooth. So yeah, “do easy” or “slow is smooth, and smooth is fast” aren’t as esoteric as they may seem at first.