Minecraft wiki entry for Things_not_to_do, associated text: In addition to this, the player is recommended to not store items that have no use other than being crafted into something (e.g. iron ingots) or being expended (e.g. arrows) in their hotbar, clogging it with unusable items. During travel, the bundle can be used to store stray items like flowers, seeds or other items that you have in ones or twos but still fill an inventory slot.