It is not a Cert' requirement,except on the three-engine ferry case(four engine aircraft)
with the DC8/B707/B747/corronado,whereas the 'perf' weights and flap settings were reduced to try and save a 'second'failure during the Takeoff.eg; the DC8 2engine out VMC was about 155k,with up to 10* of bank to the 'dead'side,and on the ground the assymetric engine was not at 'TakeOff' thrust
setting until VR-to avoid compounding the Dead engine drag.With reduced flaps(max 25*)-the higher speeds covered the VMC case.This was a regular occurrence in the 60/70's ,but was gradually phased out when only 'Check pilots' were to perform them(Big Bucks)