Tree items in settlements scrap into 10x of every type of scrap in the game. When you build something in a settlement & you have scrap already in its workbench that scrap is multiplied by 10x each 1. It is therefore impossible to run out of scrap in the game once you scrap a tree item as it will give you 10x of each type of scrap into that settlements workbench when you scrap it. This will make your life so much easier not having to loot everything you see like I generally do being I am a waste not want not kind of guy and all.