He almost missed the 3rd belt even with Stampede doing 3.6 million damage (Serpent Pet). His 5th belt with Drums was as close and would have most likely missed it had his cloak and meta not done 1 million damage combined.
I would call this lucky more than a "cakewalk"
Soloing 1,4 and 7 if you even needed it is up to AoC, then you have 1 more with Sampede. Drums is 50/50 and outside of this even with every other CD you are still relying on your HT/TED trinkets, meta or cloak to push you over the line. For a guild which has this on farm and is doing 4-5 belts its not an issue to have 1-2 wipes until it works, if your doing progression on this boss you need something a bit more concrete.