That depends on how long they are in surgery, I'd think. And isn't the reason for switching masks not because of adverse affects to the surgeon, but to protect

That depends on how long they are in surgery, I'd think. And isn't the reason for switching masks not because of adverse affects to the surgeon, but to protect the patient? We have similar things with rubber gloves: You don't need to change gloves so often if you are, say, cleaning.