On full scale planes the ailerons are attached together via cable and stick. When one goes up it opens the face of the spade and the air grabs it and assists the pilot with moving that aileron only. The other aileron (going down) is like putting your hand out the car window going 90 MPH, the load increases. this wont work on a model because each aileron has its own driving force. Even if they were attached it would be harder for the servos to move because the down ail. offsets the up ail. It works in full scale because they are mechanical but models are electrical all the way to the output shaft and it would be pointless.
