When an engine is designed, each cylinder is perfect. Each is an exact copy of its neighbor. The components within the engine are designed to be equal as well – injectors, spark plugs and ignition coils are engineered to function the same, regardless of which cylinder they serve.
With all the cylinders the same, the engine is balanced. Of course, this also means that all the coils are subjected to equal heat and vibration under the vehicle’s hood. If the engineers use a balanced approach in designing the engine’s ignition system, why would you use an unbalanced approach to repair it?