If the Rule of Two Sith strictly followed Bane's original idea, that the apprentice surpasses the master in power through a final duel between the two?
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
I doubt Palpatine would even become a Sith if the Rule of Two were followed strictly to the letter by every Banite Sith. Not without the setbacks that happened at least.