When picking up separate pieces of Firewood or Stone, the game will insist that you character is able to hold only 1 piece of each in a 2x2 Inventory Slot.

When picking up Stacked amounts of either item, the game's 'Take' action will split the items into 2 similar piles and put one of them in your Inventory while leaving the other one on the ground.

This works correctly with stacks of '2' Firewood or Stone(leaves 1 on the ground, 1 in your inventory); but when faced with 4 pieces or more, the game will leave a stack of 2 up to 4 in your inventory, unintentionally saving up to 400% of Inventory space.