As far as I can tell, it's entirely luck based. You have to make sure you're playing your level 50 class and using your ZENITH Relic weapon, nothing else will work. It took me around 84 hours total to get 7, and has been close to 3 days now since I started trying for my 8th, and no luck for me. Best advice I can give is don't pay attention to other people getting theirs, keep at it, and your work will eventually pay off.

I don't think the system needs to be changed, but we do need some sort of word from SE about what the exact factors are for them. Their silence is what is driving the negative influence, not the quest itself