Just did 15th consecutive run this week without the ghost spawn.
It's already lost so much popularity that gathering a party is brutally slow. That should not be the case for the second best weapon set in the game!
Also the spectres that spawn when you kill something, seem to have been empowered, more HP, more damage. They seldom killed my SW before, now she's running for her life, and getting swarmed.
5-7 runs (to get a 1 in 5 chance of 50% of the set) would be closer to reasonable IMO, the challenge is the Boss, not the adds, or grind.