They have been widely deployed for decades. But also, for decades (since WW2 ?) they seem to have been effectively useless (so far ??) : in all cases that I've

They have been widely deployed for decades. But also, for decades (since WW2 ?) they seem to have been effectively useless (so far ??) : in all cases that I've been able to find (please correct me if I'm wrong), either the ship (and/or nearby friendlies) were on alert and the guided bomb never even made it into machine gun range, or the ship was caught unaware and that defense system was never even turned on. (Not counting cases where radar would have been useless because the guided bomb moved under water.)