A pilot worries about failing his/her checkride. A check airman or instructor worries about EVERY checkride they give, because those pilots confront the cold realities of flying actual airplanes in actual weather. There are no second chances on those real-life "tests." It is hard to explain how much sleep is lost or how personally heart rending it is for the check airman when one of "my pilots" comes to grief. Not one I know takes it lightly. If anything, check airmen worry more about pilots than anyone. That's why they are so "hard nosed," ....so that funerals do not ever, ever happen.