Pillars seem to have a radius around them where the player must be in order for them to start dropping after being activated. Moving in and out of this radius causes some pillars to visibly delay in their descent, which also seems to interfere with their collision as well, since I can walk sideways into a pillar that is dropping but can still stand on top of it. The collision for the pillars also seems to reset position sometimes. Performed on current patch so I'm not sure how it'd work on older ones but I doubt there'd be any difference.