8 times out of 10 the PM call the malfunction 5 kts prior V1 and the PF starts the reject 5 kts faster then V1 and we all know the final results.
How many seconds it takes to decode the malfunction, verbalizing what do you think it might be the problem, reaction time from the PF and actually starting the reject?
Don't call malfunctions. Just call FIRE or FAILURE. No decode/decision to be made by the PIC in the LHS, just stop. Our machine accelerates at about 2.5kts/sec: 5kts = 2sec. Just right for the start of the stop
at V1 after the call.