I don’t have a single answer for this next question; I do have a bunch of possible answers and even more follow-up questions. Read the question. Think about it. Then send in your comment and we’ll compare thoughts on the subject.
What is the best thing to play in those situations where you have only a very short time to warm-up, e.g. before you go on stage for a performance (recital, band, orchestra, chamber music) or for an audition, etc.? You only have, oh, 15 seconds. Or 30 seconds. A minute, max.
Ideas that you might address in your answer(s):
What do you usually play in those circumstances?
What is the optimum thing to play?