Wax will give better results if you can polish & buffer it all over the surface and that too in a good manner. Applying via hand can be tiresome and not always do the in-depth job. Using a machine to apply the wax saves you time & energy. Also, it gets the job done in a much better manner. The only thing that you must know is that using a polisher or buffer will only work if you know how to use one. One wrong move & you can hurt your ride.