I would say if you really did all the dungeons on the way to 50 you will find that each instance has something to teach you.

Sastasha teaches you adds during encounter, Coppermine teaches you to dodge red indicators, Halatali teaches you about patrol mob and phase shifts, Tamtara teaches you about poisons and tanking away from your party, Qarn teaches you to watch debuffs, keep calm and situation awareness, Cutter Cry teaches you to watch cast bar on top of red indicators. After that you have Stone Vigil which puts multiple criteria to test with addition to sudden ambushes, Dzemael which unfortunately being trivialized if you get AF1 gear still has some minor mechanics and lastly Aurum Vale which is a dungeon where if one role is weak the other must compensate for you to pass the dungeon.

And to some extend Guildhest will cover things you need to know which are also things that will be applied once you reach Coil of Bahamut