While this trick doesn't give you guaranteed orange, legendary or gold weapons all the time, it is a legitimate MMORPG style item farming trick that is much more active and enjoyable than sitting around for 5 hours and waiting for a box to stock with an item you may not even want. With this trick, you can easily open at least one level 3 Metal Chest per minute, or 60 per hour, which in turn, greatly increases your chances of a rare item, and is much more enjoyable than simply sitting and waiting in the same spot for hours on end.
This trick is much more enjoyable when friends are also doing the same trick. After all, Dead Island: Riptide is supposed to be a co-op game!