[QUOTE=RealityChuck]
Just In Time warehousing barely existed in the 80s. Most mail order manufacturers did indeed keep large stocks in warehouses. Remember, the infamous Thor Power Tools decision was in 1979, and the wording predated that. Manufacturers could depreciation unsold stock and pay taxed on the lower value, making it less of a burden to keep stock around.
In addition, the biggest innovation in mail order was not the Internet, but in bar coding of warehouse items. The process of finding items in a warehouse is much quicker now; it might take half an hour to fill an order that now might take ten minutes. The longer time meant things got backed up.
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This bears repeating, I worked in a manual production inventory environment for a few years that was eventually converted to barcodes and scanners. When we started, finding a piece of inventory was literally, pull out the binder, and flip pages looking for the pallet it was on. If you remembered what area of the warehouse it was in you could narrow it down and start checking the pallet sheets for that area first. Once you located the page, go get a forklift driver to pull that pallet down for you, that might take 20-30 min for them to get around to it. Once down, dig through the pallet looking for the item, may be as many as 50 different items on a pallet, and plenty of times someone neglected to properly log the removal of product prior to your search. So you get to make a correction and place another request for another pallet to be brought down that supposedly also contains that product.
Bingo! You remove said item, note change in quantity on the pallet sheet on the pallet as well as the pallet sheet in the binder. Then you toss it over to assembly. There could be hundreds of these pulls to a single order. Then you cart it over to shipping for them to box it up, write out a label, fill out the bills of lading, and queue it up for to pick up.
All told it was not uncommon to see orders sit for a few days because several shippers offered significant discounts for larger pickups.
When it takes 20-25 man hours to pick parts, assemble, and process for shipping you tend not to even bother releasing the order to the warehouse floor until the check clears, and before the 80’s that could be several weeks by itself.
Warehousing and production supply chains have been evolving at a rate similar to the world of computers because they are massive information handling problems. So moving from 4-6 weeks to tomorrow morning is a hell of an improvement.