I really wish we had an option like Sea, Stone, Sky but for various phases of raid/EX mechanics. So that we can practice on our own. It would be the same arena as the main fight, the "team" could be made up of NPCs that would get KO'ed but not killed (scions perhaps?) and this way you can see how the boss moves, how to dodge different things and basically just learn the mechanics at your own pace. I know that defeats the purpose of the MM part of MMORPGs but if you want players to "git gud" but also don't want them making you lag behind, give them a way to practice that doesn't involve sparring dummies.