It just helps the panel remember who they interviewed. If you don't send one, it may be harder for them to remember who the heck Billy Bob was. But, hell, if you have one of those faces like mine (the kind where your mother had to lie to the police and say she was trying to teach you to swim in the two inches of bath water she held your head under...(there is that line again)), then hire someone. Just send it; some schools will actually take it on site no matter what.