I always though the 17.even.xx was AP1 and 17.odd.xx was AP2 and not related to the week which it was released. Owning an AP2 model x, I always notice that I get the odd numbered updates and not the even.
I think that was only the case until Tesla got all cars on the same code base. Which is why 17.14.23 has been deployed to all car types/ages. (But we always thought the middle digit was the week.)