Why the dark store packs the far order first

transcript

Two orders hit a dark store in the same second. One home is 600 metres away. One is 2 point 4 kilometres. Which gets picked first?

Instinct says: whoever arrived first. Or the near one, it's quickest. But arrival order ignores the one thing that differs. The ride. So the queue sorts by a deadline instead. Its pack-by time.

Start from the time you promised the customer. Subtract the predicted ride. Subtract the handover. That's when the bag must be packed. Pickers always take the earliest pack-by. No exceptions.

The near order has a short ride. Plenty of time in the store. The far order has a long ride. So far less time in the store. So the far one gets picked first. And both arrive on time.

And here's the bonus. An order that's running late? Its pack-by is earliest. It gets picked first, not last.

The pick list follows a walk. Fast movers sit nearest packing. Ambient aisles first, frozen last. Cold items spend least time out. Every item is scanned into the bag. Seven lines: about 145 seconds.

The far order goes first, and nobody is late. Sort by deadline, not by arrival.

Full breakdown in the lecture.