Are you playing with a banjo? If so, then consider doing three or four songs in the same key before changing-- it will take a long time to change keys since the capo needs to be moved, the 5th string retuned, and the other strings re-tuned because on a banjo you change one string, you gotta change them ALL. And this is distracting when performing.
If you are singing w guitar, then feel free to move capo around and change keys on every song!