Lets assume we are working on dual elevator servos and you have the same length arms on the servos and your control horn connection on each half is the same distance from the surface.

Now lets take a control rod with ball links on both ends and the total distance from the center of the hole to the center of the other hole in the ball links is 3 inches for both setups. With 1.5 inch servo arms you might be getting 45 degrees of throw

Now lets take the rod on the right elevator and turn one of the ball links 1/2 turn outward. You have now moved that surface maybe 1/16th of an inch up. So now you adjust the subtrim to conpensate and recenter the surface. Now remember your right rod is just a bit longer.

Ok so now you do the stick trick and notice that the right side is getting to full through faster because the rod is longer but you adjusted your ATV's to get the same throw which you do get but the plane now rolls slightly right in the air because the longer rod is moving the surface to full travel faster. The reverse is true when inverted or the rod is shortened

Hope this splains this for ya