Originally posted by Nephthys
Obviously it doesn't since esoteric abilities don't require that.
Like I said, the more relevant issue to this thread is that each apprentice has to be better in overall combative ability than their master, and this aggregates.
We should also acknowledge that although the would become stronger, Sidious and Plagueis killed their masters without power being an issue. Backstabbing and surprise are just as possible as direct conflict.
Yes, it doesn't always happen that way, but it happens frequently enough for it to add up. And Sidious and Plagueis are interesting examples - they didn't kill their masters in direct combat but were still noticeably more powerful in their primes.