When repeaters fail in an emergency the standard action is for stations to transmit on the output frequency of the repeater, not go seeking another simplex channel. This action is very simple, press one button to cancel the frequency shift setting.
The important point is that all the other stations responding to the emergency will be listening on the repeater output frequency, expecting it to be operational, rather than some unknown simplex frequency. If the repeater comes back with emergency power or whatever, the net is already there on simplex in progress, just enable the shift and continue with no actual QSY required.
We all know how many stations get left behind when a large net is asked to QSY.... if the new frequency is bad (busy or has interference) another QSY will lose even more people... because either they don't hear the instructions, the new freqs are not in memory, or hams forget how to dial in their radios.
