Many years ago I was in a NYC club listening to the Phil Woods Quartet ... At the time he had an album out with the Janis Ian tune "At Seventeen" that had gotten a fair amount of play on the jazz station I listened to. My wife and I were sitting at a table right in front of the stage and from time to time Phil would 'chat' a bit with the people in the front ... during one of thos 'chats' I asked him if they would play "At Seventeen" ... he replied "I'm sorry, but it's not in tonight's book" ... now these 4 guys probably could have played it cold and done a damn good job of it, but because it wasn't what they had rehearsed, Phil wasn't playing it ...