Interestingly enough, Toyota modified their supply chain operating model post-Fukushima. So the solution isn't as coarse as a binary "stockpiles or JIT", but an intelligent assessment of risk and managing that risk granularly. Kaizen at its best.
"Toyota may have pioneered the just-in-time manufacturing strategy but when it comes to chips, its decision to stockpile what have become key components in cars goes back a decade to the Fukushima disaster."
"After the catastrophe severed Toyota’s supply chains on March 11, 2011, the world’s biggest automaker realised the lead-time for semiconductors was way too long to cope with devastating shocks such as natural disasters.
That’s why Toyota came up with a business continuity plan (BCP) that required suppliers to stockpile anywhere from two to six months’ worth of chips for the Japanese carmaker, depending on the time it takes from order to delivery, four sources said."
"“Toyota was, as far as we can tell, the only automaker properly equipped to deal with chip shortages,” said a person familiar with Harman International, which specialises in car audio systems, displays and driver assistance technology."
https://www.reuters.com/article/us-japan-fukushima-anniversa...