I’ve had 50% hit/miss groups with pugging. This lines up perfectly with standard bell curve distributions. Half of the players are going to be below par, the other half, above par. Can usually still time anything under a 14 with little problem, so long as 2/5 people are decent (healer and tank or one dps)
I’ve gotten KSM multiple seasons only pugging and didn’t have to spend like 30 tries on an instance to finally time it. I think the worst luck would have been Tol Dagor in BfA, and that took around 5 tries to finally time a 15 on. But that had more to do with the instance being buggy and pulling crap through walls or even whole floors.
Point is, I’ve seen some amazing pugs and some horrible ones, but that’s just how it goes. I recommend using RaiderIO and paying attention to stats for things like the number of timed runs in a bracket.