Exactly! If it's anything like playing the guitar, then the reason she's faster, is due to her technique: the subtlest differences in the way she forms her strokes and the way she uses the paddle. Things you can't tell just by looking, very tiny differences in the timing, speeed, angle, and paddle depth. Like the guitar, the only way to learn those things is to practice over and over again, and your body will slowly learn the muscle memory of which tiny little precise movements result in more forward motion with less expenditure of muscle energy.

Any beginner guitarist will tell you that it hurts their left hand. Not just the need to develop callouses on the fingertips, but also just the overall muscle soreness. But an experienced guitarist can play for hours before developing any fatigue at all, and the sounds they make are cleaner and more precise than those of a beginner. The reason? The beginner is expending massive amounts of concentration, muscle energy, tension, and pressure, in ways that they don't need to be. Their muscles haven't yet learned that they're wasting their energy in those places. The beginner tries to play a note or a chord, and when it buzzes or mutes unexpectedly, they are (correctly) squeezing harder to get the string pressed against the fretboard more firmly, which results in a cleaner note, but much energy wasted. An expert guitarist can make those cleaner sounds with the gentlest of touches and the most subtle of hand movements, with much less muscle energy expended overall, because years of practice have allowed them to work smarter, not harder. They have learned the exact angle and location to position their fingertips to get the strings to press against the frets precisely right, with the absolute minimum force necessary.

I'm sure that any physical activity which requires any kind of finesse will be exactly the same.