To begin, I'd like to preface this question / report with the intent to not sound like crying or raging. This is a concern of mine that seems to be surfacing with the newest content: Ultimate Naverius.
I am currently playing with a group of three: my brother, one of my buds, and myself. We all got to 75 about 5 days ago, and headed immediately into farming for the Nemesis gear. We did the typical rare drop stuff, like getting dailies to max, popping 100% triboost, 250% rare boost, alliance tree, party with 4, etc. Also to mention most of these runs went very smoothly; 12 people zones with great players with good mobbing and bossing potential (for example, went to take a 30 second bio break, a diaboigryph had spawned and died before I got back. Awesome party ).
After the 5 days of farming, I have found a single 13 star, while my brother and buddy have found 6 Nemesis weapons and 2-3 Gix weapons each, and my brother found 2 of the three ray armors. Besides 13 stars, each have found plenty of sigma weapons, and enough deo weapons to fund the next set of 250% rare boosters, while I have found maybe 5 sigma weapons and maybe around 15 deo weapons.
I know people get lucky / unlucky, but I don't think luck is a constant thing. Like it is certainly possible to roll a dice and roll a 1 every single time, but to do so consistently every day for 5 straight days seems a bit much. The most recent frustrating thing is we even had a joker spawn in the map, and I think my rare drop rate was like 850% or something dumb like that, and not a single rare dropped, not even a 7 star. I know a bit about how the drops are calculated, and that 13 stars are rare at the moment, but to see everyone getting them, even the rando that joins our party to make it 4 people, is a concern to me that something is bugged with my account or something. I understand that this sounds whiny, but I am just generally concerned that it's a "me" issue since I see the rest of my party getting these drops.
TLDR; Not really getting rare drops when everyone else is getting plenty.