I wonder...
Let us suppose that it is the Captain making the takeoff.
The First Officer makes the V1 call, and at the same time 'bang', there goes an engine.
The Captain continues as he should, but is he listening specifically for the First Officers V1 call, or does he primarily depend on what his airspeed indicator indicates?
In other words, is he depending on the call?
Personally, I do not.
At heavy weights, I have already determined (approaching V1) that I will more than likely continue, as I have absolutely NO intention of sliding off the end, following a high speed abort.
Several years ago departing FUK, at max weight, I asked the First Officer if he thought we could stop safely, with an abort just before V1.
His answer was...'not likely Captain, we surely would end up in the drink.'
He was more than likely correct.