So it's now December and I've been complete at about 10 schools since September and still haven't heard anything. Would it do any good to send a letter of interest or update letter to these schools? I'm getting more and more nervous as each day passes
That depends on which schools you are looking at. Interview season is winding down at some schools and they will be done handing out interviews in a few weeks. Check with each school and see when interviews will be handed out and then decide.