When you try to calculate the compound probability of multiple events you get into VERY large numbers indeed. Like millions to one.
The perfect scenario would simply never occur in any reasonable time frame. I'm talking about (at least) thousands of years of play,
probably more.
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You still have the possibility of someone whipping out a dosed pet and getting the full duration
of the beneficial debuff. Not to mention dozens of other exploits which most people don't even
know about which are probably already being used.
In truth even without any exploits at all, there are always going to be ways to game the system.
The pro raiders site mentions the issue of boss skipping-that's one of many issues that can only
be partially solved as it is debatable what a truly "fair" solution is.
If I had any interest in doing this at all I'd try to get to the top rank by using very high variance
infrequently proccing trinkets etc and hope to get a fantastically lucky streak. My chance of
topping the charts would go up exponentially but it would be very little to do with my actual
skill.