Is your intent with spells that they be one-and-done, or are they like an ongoing piece of gear where once it has been marked in inventory it can be cast multiple times without marking additional inventory slots?
Viewing post in Forged in the Dungeon comments
My intent is to treat it like gear. Once it has been marked in inventory it can be cast multiple times without taking additional inventory slots.
However, if in fiction you lose your components associated with that spell you will have to mark off new inventory slots. (For example if you try to cast magic missile in a desperate position and fail you might have to junk the inventory slots associated with that spell.)