Yep, I agree with Sway, depends on where you are. I know that in the Indian Ocean if you're more than 100 miles off-shore, your EPIRB has about the same value as tits on a rain barrel. There is no SAR of any description, there is precious little commercial shipping other than hugging the coast and the fishing vessels don't have radios switched on unless they need to use them.
I have sailed close enough to fishing boats off Sri Lanka and Indonesia to throw empty beer cans onto their decks and they still don't answer the radio.
The flipside of that is anywhere in the South Pacific or Australasia, the EPIRB is indispensible and will be reacted to in very quick order by NZ or Australia and the SAR that will follow will be a benchmark performance. NZ even today encourages owners of the older pre 406 units to continue using them if they can't afford the replacement and they are still reacted to.
But it is of considerable importance that the EPIRB is correctly registered with the correct authority, else the rescue efforts will be compromised.