Slow practice is not easier — it's harder and more effective
Playing slowly forces your brain to consciously process each movement rather than running on motor autopilot. When you practice at speed, errors become embedded in the muscle memory. When you practice slowly enough that every note is deliberate and correct, you're building a cleaner neural pathway. The rule of thumb: practice at the speed where you make zero mistakes, then increase tempo by 5% increments. This is how concert pianists learn 40-minute concertos.
Speed is a byproduct of accuracy, not something you practice separately.