Shure rubber donuts are nice as far as they go; for wireless microphones they'd probably be just about perfect.
But for microphones that are used with cables, a shock mount should isolate some length of the cable along with the microphone. And the foot or so of cable where it enters the microphone needs to be fairly slack, so that it doesn't become a conduit for vibrations. It also should not restrict the freedom of the microphone to move within the range that the flexibility of the shock mount allows.
There seems to be a lack of awareness about this among live sound engineers, unfortunately. It's common to see a microphone sitting in a shock mount, where the cable comes out of the microphone without a slack loop being "pinched off" at any point--and the cable is then wrapped around the boom arm. This defeats much of the purpose of the shock mount, unless you think of it mainly as a fancy decoration.
--best regards