Some people have done 80 clears and no drops. I didn't even keep track of mine. At this point, Bungie should just swap back to exotic quests with Dungeons like Gjallarhorn or Xenophage instead of this low drop chance with triumphs increasing said chance by a barely noticable value. Some people would probably say that would remove a reason to do the dungeon again and my responce would be that it shouldn't be because of the exotic you come back, it should be because of the fun the activity should bring. Unfortunately, Bungie's current changes with adding minus power to them just lowers that fun value so there is even less of a reason now.