so you are trying to tell me that rope overhead tri ext dont stress the long head better thab kickbacks?
or that hammer curls dont create more bicep width the concentration curls
EMG test shows amounts of activation in muscles when completing exercises, some recruit more fibres than others, true.
However this doesnt mean that ones with lower muscle recruitment are shaping exercises, not mass builders - they may be less effective, but not differentiated from.
Tell you what, if you trained to all out failure, it wouldn't really matter what exercise you picked for such a small muscle group, it would all get worked to a degree.
I hardly do compound for triceps anymore, yet they still grow, not change shape!