6 and 5 are also references to Atlantis due to Poseidon worship.

https://www.sacred-texts.com/cla/plato/critias.htm

Each of the ten kings in his own division and in his own city had the absolute control of the citizens, and, in most cases, of the laws, punishing and slaying whomsoever he would. Now the order of precedence among them and their mutual relations were regulated by the commands of Poseidon which the law had handed down. These were inscribed by the first kings on a pillar of orichalcum, which was situated in the middle of the island, at the temple of Poseidon, whither the kings were gathered together every fifth and every sixth year alternately, thus giving equal honour to the odd and to the even number.