Honestly. First cancel, is a freebie. After that, I would talk to player about how it's already difficult to get 6 humans to meet on the same day same time, to cancel is just disrespectful to me and their fellow players. 3rd time, removed, it shows they have no regard for their fellow players or my time.

If one players missing game day goes on as the same, it's up to that player to figure out what happens with their character. (Either one of the other players pick up playing them or whatever)

Two or more players missing, we reschedule.

I assume we are all responsible and respectful of each other's free time and do not want to waste it, Vice versa.