What is the primary aerodynamic purpose of using a balance tab on a control surface to maintain steady-state flight?

The primary aerodynamic purpose of a balance tab is to reduce the physical force the pilot must apply to the flight controls to hold a control surface, such as an aileron or elevator, in a deflected position. A balance tab is a small auxiliary flap attached to the trailing edge of a primary control surface and is linked to the fixed surface of the aircraft. When....