For me it's just one of those battles that shows up way too often in roulettes, even when there are no new ppl. It also doesn't help that the fight is simple and super fast but no one wants to follow instruction or do mechanics properly which makes it take much longer than it should. Tanks are always holding the adds off in lala land, while the dps ignore the boss until they are dead and no one wants to man the cannons. If you hold the mobs under the boss and have everyone focus on the boss while 1 healer and the off tanks use cannons to take out the adds and damage the boss you can have him down after 1 dragon killer. Quick and faceroll easy.

Steps, Mog and Tsukuyomi seem to be the worst offenders for trials, just like 1000 maws is notorious for popping for leveling. I know SE says they do not weigh the roulette toward any set of fights or dungeons, but there are battles and dungeons that either have never or only once or twice ever popped for roulette unless there was someone new to them while a small handful of others show up 90% of the time. I actually kept track once and after 1 full month after noticing a pattern over the course of months and steps, mog and tsukuyomi popped 24 of the 31 days for both my chars. So yeah, even with the law of random, the probability of that is low if they were not weighted somehow.