Hmm I got super lucky with the Crux of crota, got it twice in a row on the second week of hard Crota, my team was going crazy XD and now I even have 2 Crux to spare. Because bungie said that it would be less likely to get the same loot on crota, what i did was have all my guns with me (even eidolen alloy) and also the Glowhoo shader, maybe that would also work for you. What I also noticed is that every character can hold 1 Crux at a time (and 1 in the vault) so if u would play with people who allready have the crux in their inventory the chance that you would get the crux next would perhaps be higher(?)