The raid group I'm in, it took about a week of proper training in a call and everything to learn the O5S fight (Since we raid about 2-ish hours a day, 2-3 days a week), in O6S took like a week later, and in O7S, we keep having around 1-2% wipes because of the crazy amount of microlag that seems to happen in the fight.

In comparison 5/6 are rather easy to get with enough communication, but 7 is a whore of a mother.