Not to criticize the concept of JIT to avoid excessive inventory, but I've always argued that the flipside of JIT is turning every path in the supply chain into a critical path.
I feel like this is the manufacturing equivalent of the financial sector shenanigans back in 08.
A bunch of companies increasing profits by baking in risks into the chain, because the risks of your individual providers failing are independent probabilities, until a pandemic closes them all at the same time.
The obvious difference is that the financial sector was (and is) way bigger than manufacturing.
Yeah JIT is a bit suspicious. I also think there is some planned obsolescence that is making the inventory depreciation so scary the bean counters to begin with.
e.g. microcontrols don't require lots of processing power, and if embedded software wasn't complete shit it would be easy to keep portable so there is supply chain flexibility.
Just-in-time manufacturing came from automotive, which has a long history of the major automakers exerting tight control over their suppliers. Really tight control, like the ability to send in inspectors for a no-notice quality audit, and the right to look at a supplier's financial records. That control has loosened in recent years, as suppliers have become bigger and not totally focused on automotive.
If you have a just-in-time manufacturing operation and your suppliers are more powerful than you are, you're very vulnerable.