Sort of true Scott, but muscle tone is part of it, a toned muscle reacts to response better that an un-toned or tired one.
A reflexed response does not suffer this problem because it uses a different type of trigger (stimuli).
But for playing you have to think, you have choices and you have to make the correct ones. Mistakes come from making the wrong choices, moving the wrong fingers at the wrong time, moving the right fingers at the wrong time, moving the wrong fingers at the right time etc..
Certain aspects of playing are reaction because we simply cannot think that fast, so it is learned slowly and deliberatly as a group pattern. We can play a patten but not think about the notes in it because we recognise the pattern and react to that, transposing around the neck shows us this.
In sight reading we learn to recognise grouping of notes and know how they should feel, so when we analyze them closer we are in fact reinforcing the notes to be played with in the grouping, to the feel that is written. Again this is breaking things down and slowly letting the brain organize them, then put them together in a manner we can understand and relate to.
As already mentioned speed is a by product of smooth, accurate, and fluid playing skills, with no doubt in the mind as to what is going on.
