It would be more practical to ask an electronic engineer about that. If the final stage of the amplifier cannot deliver damaging power then no amount of input will change that fact.
Often limiting is done by diodes, alone or in an active circuit. Diodes clamp the signal within nanoseconds. For audio frequencies this means "instantly."
I always use earmuffs; I have an excellent pair of passive earmuffs, very light and with high attenuation. And I have a pair of electronic earmuffs; the attenuation of those is not as good just due to manufacturing. But the amplifier is flawless, and I can hear more in them than without. This is important because you need to know about vehicles and people that are moving nearby.
I never doubled foam plugs and earmuffs. But the loudest calibers I have are .223 and 9mm. Hunting with 9mm is not something I practice often, to great disappointment of the game.
Yes, but that “electrical engineer” would be making poor assumptions about the operation of the ear muffs.
There is a micro-second before the cutoff mechanism is activated.
During that period there are potentially damaging decibel levels.