We practice to create space. This is true for playing a musical instrument, but applies to everything else as well, I think. Practicing creates familiarity. Familiarity creates intimacy.
When we practice playing a piece of music or a scale, we train our brain by using our body. We scrub those neural pathways by moving our fingers. And that creates space. If moving from this note to that note has been trained and ingrained, we no longer have to think about that move and are free to consider other or additional moves. If moving from point A to point B has become utterly natural, then I have established space between those two points in which I can make additional moves. Or, imagine jumping from a rock to another rock. Once that jump has become easy, we might add a turn, a twist or a salto. In music, we might add a new note, a trill, a tremolo, a vibrato… We have created space (or time) in which to make additional moves – or choose not to! The more natural that jump or that piece of music becomes, the more space we have created. Then we have more time and more choice.
I find it important that the space we have thus created should not necessarily be filled with additional notes as we can use that space to embue the sound with more intent or emotion instead. When we no longer have to work at getting to the next note or musical sound, we can enjoy playing the current note with complete conviction.