Right at the start of a game, I got my guys to chopping trees. I promoted one to the Carpenter. While the carpenter was carrying wood back to the stockpile, I told her to build a workshop. The carpenter proceeded to drop her piece of wood right onto a block of stone in the stockpile and then pick up a different piece of wood to construct her workbench with.
There were open parts of the stockpile within a single step.
Presumably the “emergency item dump” routine needs some work to prevent hearthlings from dumping items on top of other items in the stockpile if they happen to be there at the time.