The V1 call in simulator training general, is normally made by the PM. From personal observation the vast majority are called slightly late and I have never observed an early call. By slightly late, I mean one second or more after the ASI has gone through V1 and I am not talking about the deliberate V1 minus 5 call under discussion.
It should be remembered calls by the PM for (say) 80 knots or 100 knots or V1 or VR, during the take off run are purely support calls or back-up calls. They are not supposed to be action calls. If for some reason the PM fails to make any one of these calls, it shouldn't matter to the decision making of the captain who has his own ASI.
The captain and first officer each have an ASI. Depending on the design, there may be moveable "bugs" set at V1 and VR as well as other speeds. Assuming the company procedure is the captain is handling pilot for all rejected take off procedures, then he should be well aware of V1 and that is by observing his own ASI. The PM support call is handy as a reminder and that is all.
Again from numerous observations in simulators during type rating training where the PM who makes the support calls is quietly told by the instructor, to "forget" to call VR, we have seen some alarmingly hesitant delays by the PF who then fails to rotate at the correct VR because he momentarily disbelieves his own ASI simply because of no call by the PM.
In other words he was waiting until
being told by the PM to rotate The worst I saw was the PF staying on the runway 37 knots after the bugged VR because he was waiting for the PM to call "Rotate". As we went into the overrun and through the localiser aerials, the PF looked across the cockpit at the PM and said accusingly "You forgot to call `Rotate`"
A smart pilot will always have an eye on the ground speed reading nearing VR and knows what its approximate indication should be approaching the airspeed check at 80 knots (737) and especially nearing VR. The PM support calls during the take off roll will always be with us but as said earlier, they are back up only - not necessarily action calls.