I'm likely at 60+ times (3 level 32 characters) running Crota End on Hard and it still hasn't dropped for me. I have the Eidolon Ally all levelled up and just need that @#$%#^ Crux to drop. Ran it today with my Warlock and some guy who already has it before got it again. However he still hasn't gotten the Husk to drop, so it's useless to him.