You always have to keep in mind that fact that we are little processing plants - we take stuff in, grind it up and zap out something different. The notes that come out are affected by everything we took in - food, fluids, poisons (alcohol & drugs), air, rest - and the environment in which we're working. If the air pressure changes, your ears do to and things start to sound different. The alchemists had the right idea; yopu keep repeating the process until you get it right. That's when it's golden!

Years ago I read an interview with Marlon Brando in which he said that he always strove to give 80% effort. That way his reach never over-extended his grasp. This seemed odd, coming from a cultural background where you're supposed to give "110%", but it does make sense. It's like practicing a passage at a higher speed than you will actually play it; at the regular tempo, the passage seems a lot slower and easier.

To me, given the reality that you aren't going to have your "A" game every time, the artistry comes in being able to construct other options at a moments notice. The ability to adjust when something isn't working is the mark of the "professional" (Perhaps "master craftsman" would be a better term?). If your throat is a little raw, and you can't go for the big note (or if your fingers won't let you navigate that complicated run) when the time comes, the trick is to find some other place to go that works. I've always been amazed when working in the presence of players who never make a mistake - who always have a place to go. That is so cool. . .