That depends on where you run your linkage. If you run it under the deck, it doesn't really matter. If you run it down the engine bay, as many people do, a right side rudder will have the servo "push" the rudder arm to turn the boat to the right, which can require heavier rods to prevent bending. A left side rudder will be "pulled" into a right turn, minimizing the chance of bending. Obviously, the boat will need to be able to turn left so there is still the chance of having the rod flex regardless of which side of the boat the rudder is on.