I agree. When I used to do C of A air tests after any kind of major maintenance, we always did a flying control check which required one of the flight crew, usually the flight engineer, to go outside with a headset and long lead while one of the pilots moved the flight controls in a clearly defined sequence. Each of the control surface positions (ailerons and spoilers, elevators, rudder and stabiliser) were reported and correlated with the pilot who was manipulating the controls in the cockpit.
Isnt that why the numbers and ticks are painted on the flaps and elevators?