An order lives for months. Deposit taken, fabric chosen, supplier confirmed, delivery booked: each stage has a date, and a customer who has heard nothing for six weeks assumes the worst regardless of the truth.
Supplier slippage is normal and manageable, as long as it is visible. The damage is done when the shop learns of a delay on the day the customer expected the sofa.
Delivery is a logistics job in itself. Route, two-person crew, access notes and the removal of the old piece all belong to the order, because the crew arriving without that information is where the reviews are lost.
Stock means two things here. What is on the showroom floor and what is in the warehouse behave differently, and treating them as one number is how a display model gets sold twice.