I think Palace of the Dead is a good example of a never changing formula. What it draws inspiration from, Nyzul Isle, was content that random objectives on each floor that often had you focusing on something besides combat. XIV's implementation of that removes all those objectives and puts you straight back to "defeat the enemies to progress" just like every other piece of content for DoW/DoM in the game. Between this and Aquapolis, they've designed content with random enemy patterns and such to vary up fights being the same each time, but that's as far as they went. There's nothing beyond "fight things."