Mark Knopfler of Dire Straits fame is another one of those whose can do amazing things without having to practice much, or often.

In my case, I find 2-3 hours during the week, and another 3-4 over the weekend, is enough to maintain my current unexceptional level. When I try on something new, though, my left hand does this 'spastic spider' routine :D until I get things smoothed out.