Stop applying logic and common sense to the situation. Why stockpile parts locally when Lean Six Sigma Just-In-Time Supply will almost get you the parts you need 100 percent of the time?
JIT and L6S are solid "concepts".. For industry. When you know what you are making a month out. And you have great statistical failure on the MTBF on parts.
Oh, and all these factories that have are JIT and LEAN.. They keep critical spares for machines on hand.. Raw materials stretched any more than pseudo JIT.. Well, you are one wrecked truck or bad storm away from losing your ass to your customers who are counting on you to be JIT to them.
A flat tire on a Semi on the Mass Pike in 1998 cost my company (POLLAK) upwards of $750k.. Why? Because it held the JIT delivered housings needed to make 4WD disconnect actuators for GM fullsize trucks, and that truck being 6 hours late shut down our line, so we were 1000 units short on the scheduled truck headed to AAM in Detroit, which made them late on their delivery to GM Truck Assembly in Flint, MI, which then back billed us for the 3 hours their line was down waiting for parts we bought seats on an airliner for (I got to fly with the bags of parts).
We were billed at $250k an hour for every hour the GM plant was down.. For all the AIRSpeed and L6S shit I had to do in the Navy as QAO and AIRSpeed goon for 121/CAG7, I tell that story about the dangers of cutting JIT too close.. And they never listen..
And the COD delivering your parts will never bump them for an Admniral who wants to come to the boat.. Never. Or just plain break down.