Personally I'd give dungeons a totem system like ex primals. RNG is RNG and I believe there should always be a buffer for that RNG. While helping my tank gear up for UCoB, we ran Swallow's Compass something to the tune of 40 times, with no exaggeration, looking for her tank boots. Just one singular drop, and of all those 40 times, it only dropped once (on the last one).

Yes, RNG is RNG. But there should be a buffer for it; there is in the leveling dungeons, with guaranteed drops (heck, I don't see why EX dungeons couldn't have that--not like the gear from there is good for much except the odd one being good for last tier's Ultimate anyway).