McCoy's trick might have resulted in some gradual changes to the ritual though. When Spock thought he had killed Kirk, that was enough to snap him out of it, without the final blow being lethal. Perhaps Nerfed ahn-woons and lirpas were later used, or the opponents were given some sort of delayed action knock-out drops.
Two thoughts on that:
1) If the combatants know it isn't a combat to the death, will it have the same chemical effect on the Vulcan brain?
2) How much did Spock's human biology have to do with the fact he didn't need the sex for the effects of Pon Farr to wear off?