I have ran 10+ horde with 10 wave each. I hard build into elites and hellborne with few masses and all I get are Soulspires, hardly get any hellbornes at all when hard build into them always spire after spire. Bad RNG or just bugged?
Also how does it make any sense that 3 Aether fiends spawn immediately, but the fiend when you fill the meter takes 3-4 seconds to spawn and you have to be near it to start spawning!
For a timed event you are trying your hardest to waste time on things not related to gameplay!
Bad RNG. I get a lot of Hellbornes in Infernal.
I also get two Butchers spawning in one wave lol. That’s was funny.
RNG is heavy sometimes. I opened all boxes in a T3 helltides today and did 10x the maiden… guess how many ancestral items i got? yes. Zero 
My worst record in infernal hordes thx to the spires: 198 points with a 6-wave stone
I also recognized: the longer i play the less and worse loot i get 
At low helltides tiers i were able to target farm uniques. Open a few chest et voila i quickly got my stuff for my build.
Now i only get legendaries from the helltides chest in T3 
Maybe theres a “paragon check”. If you got 200+ paragon points you dont get good stuff anymore in T3 being a big sign to exclusively convert to Torment 4 