Pulling In a Calendar: What Each Day Costs and Which Day to Stop Buying

How to read this sheet

Read the binding path column before spending anything. A chain that was not the longest on the day the order was confirmed can be expedited at any price and the ship date will not move by an hour, and that is where an expediting budget usually goes - into the chain whose manager answers the telephone rather than into the one holding the date. On the seeded order the trim chain is seven days shorter than the fabric chain, so the first seven days of trim expediting are worth precisely nothing. The days you can crash figure is the one to be honest about. It is what an activity would genuinely give up under pressure and not what was said in a meeting: a dyehouse willing to run a dedicated weekend batch has real days in it, and an approval waiting on a buyer in another time zone usually has none at all, however much it is chased. An optimistic figure here will produce a plan that cannot be executed and a shipment that is late anyway, having also spent the money. Stop buying when a day costs more than a day late. The instinct is to hit the date whatever it takes, and it is expensive: on the seed the eighteenth day costs thirty-seven and a half thousand against a lateness of thirty-two, so the right plan buys seventeen and ships a day behind. That is a conversation to have with the buyer in advance rather than a decision to take quietly. What is not modelled. The calendar is parallel chains feeding one tail, which covers most apparel orders and not all of them - an order with a genuine network of dependencies needs a scheduler, and this sheet will understate the difficulty. Crashing is treated as available in whole days at a constant price, when in practice the third weekend costs more than the first and some activities crash in blocks or not at all. Nothing is charged for the risk that a crashed activity fails - a rushed lab dip that misses is worse than no time saved - and nothing for the disruption to the other orders on the floor, which on a full plant is the largest omitted cost here.