Delerium Simulacrum Splinter drop rates are WILDY inconsistent

Sometime I get 10-20 but often times I get a pile of only 2 when full clearing a map in fog, makes no sense. I'm doing T15s with increased splinter tablet and full delerium atlas, and shattering mirrors along the way. Even killing the unique boss spawns and several delerium rares still gives only 2 splinters a good chunk of the time... feels like something is wrong here.