I know we've had to take apart a few to get them off/on, but I also know that we've take off several that we didn't need to take apart (basically remove the screw that holds the coil). I've seen them in quite a few different styles, so I'd say you have to look at it and see if you can get that one screw in without taking it apart.
BTW - that was the only reason we had to take them apart - couldn't get at the screw that is under the knurled nut.