They're called FLOORS!

[Nadirah]

Also, the Binding Coil of Bahamut had turns, because coils wind, and each turn was a floor lower than the last one.
They weren't called turns because you alternated turns like in a board game.

Calling the new raid tiers "turns" is like me calling my wife on the way home and saying I'm just 14 doors away instead of 14 blocks, but hey, I was walking through some doors earlier, so same thing, right?

Except that a blown up moon prison to me didn't seem like a Coil of anything. Spring Coil type coil. I envisioned the raid as a series of broken she'll pieces connected by teleporters.