As you said, there are a bunch of ways to do it. Sometimes I just mount the servo and connect the push rod to the arm and horn, I always have my controls made up in advance, then find the spot where the horn mounts close to the hinge line and is a straight, linear throw so there is no binding. Sort of let the servo pick the spot. Sometimes I have just used a straight edge run from the servo arm across the control surface and marked it out. I can do it a lot of ways but I do try to get a hinge in the area of where the arm will be mounted. I do this off the plans during the build. With an ARF the arm will go wherever you can get a straight shot with the control rod.
Not sure if I said that so anyone could understand it but the key is NO BINDING.