Practicing Guitar some

The corporate band is starting up again, so I've been practicing and playing guitar a bit more than I normally would.

I guess I wanted to post a bit about memory, or muscle memory, or whatever it is. The last time I played the lines in the song "Smooth" (Santana/Rob Thomas) was about 6 months ago. It's amazing how a quick refresher can bring so much of a song back so quickly. And beyond that, why would my mind remember (with brief refresher from tabs) so well something so intricate as guitar lines from 6 months ago - guitar lines that I hadn't played once over that time period? And how long would that kind of memory last going unused?

From an evolutionary standpoint it gets me to thinking about seasonal things - like something you only do in the spring and forget about until the next spring rolls around. Are we wired to hold on to these learned skills for 1 year? 2 years? How long was it adaptively useful to program us to remember these things?

And does this type of memory preclude other new learning? Example: If my brain is saving the space for "Smooth" - is it preventing that space from being used for other perhaps more useful things?

Anyhow, that's the wondering of the day.