I'm wondering how important a coil cover is to protect the coil on a metal detector. Coils cost quite a bit to replace but I don't think anybody I've seen detecting had a cover to protect the coil. How many years of detecting can you get out of a coil on various surfaces {grass, dirt, gravel} without a cover, before it's dead. From the way they look it seems like it would take a lot of use to damage one. What percentage of people use them? I'm thinkin not to many. Thanks for opinions.