I think you've just been lucky since then. If loops in power cords were effective, surge protection companies would be out of business, and I spent 8 years in the Navy working on electronics as well, and never heard or seen that done. Without a lower impedance path to ground, all the loops in the world won't do a thing. Ground rods are the most important part of the entire process. A lot of folks drive a round fencepost a foot or foot and a half in the ground and then wonder why the fence isn't hot or why it burns out during the first thunderstorm. 3 loops in a cord may increase inductance a slight bit, and might help with everyday minor voltage swings (that shouldn't hurt a charger anyway), but they'll do nothing to combat a true damaging surge and will only shorten the life of your cord, especially if it's out in the weather.