That is 81 of the same type, not 81 total.. Obviously that amount decreases with gear and difficulty.. ie now that I have 1M dps and farm torment 2 the next flawless royal probably will be significantly less than 30 hours considering imperials shorten the time a fair amount. Still it is 6 random stats.. For example if a wizard made a chest and didn't get 3 of int/vit/armor/socket 3/all resist with 4 primary stats it would pretty much be a paper weight that cost a flawless royal.
TLDR Flawless Royals are not an acceptable mat requirement for anything that isn't guarenteed to be good, or potentially BiS.
The demonskin drop rate is irrelevant.. most of the legendary items require time to farm.. all they need to do is make him spawn in a random location in the zone to fix this.. or they could just make him not spawn after you have the checkpoint. This method is fairly terrible experience... probably not better legendary farming, though it is decent. I've been doing it abit because i can do it with barely paying any attention while watching a movie, something I could not do while farming a torment 2+ rift.
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TLDR Flawless Royals are not an acceptable mat requirement for anything that isn't guarenteed to be good, or potentially BiS.
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Ignoring gold(which most people can't ignore) a flawless royal takes like 30+ hours of farming just to get enough gems.
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