I just ran out of battery power while using a cordless drill.
Luckily, I didn't have to stop my project, because like most cordless drill users, I have 2 batteries. Whenever one runs out, I just pop on the backup. The spent battery charges while I keep going.
Having a 2-bin system in place is the same way with materials and WIP in a production system. You never need to stop a project to make more of the material you need when you have a full extra bin ready to go at all times.