But Band, you keep overlooking or avoiding the fact that I already have a plan to transmit on 121.5 (and 406): with (1) the ELT fitted to the aircraft (1 second to switch on) (2) the PLB on my hip (3 seconds to extend the antenna and push the activate button) in accordance with practised procedure and (3), if I have pax, by them activating the spare PLB in the pocket behind my seat in accordance with the pre-briefed procedure.
If there is anyone in range to hear the beacon/s transmitting on 121.5, there's a fair chance they'll be in range to hear a MAYDAY on Area.
Then there's my HF that's already tuned to the Flightwatch frequency...
If people are flying around in remote areas with old ELTs and PLBs with time expired batteries, that's relevant to their procedures in an emergency, not mine. Charles Darwin will deal with them.