At Augusta Vocal Week I saw a concert given by students in a class about building confidence. They sang their "solo" parts two by two, which I thought was neat (they were singing for about 400 people.) I figure each partner gave the other something to lean on, added strength to the sound, took a little of the heat, and besides that, you wouldn't want to let your partner down by collapsing and being unable to sing.
Thread creep, I guess, Nuff said until next summer when we start to plan.