I bought about five years of my small-scale production back in Dec 2019 (what amounted to full reels of most parts, not because I wanted five years specifically). That was driven initially by MLCC cap supply “weirdness”, but while I was buying, it was dirt cheap (well under $2000) to just buy all the components.

It’s come in handier than I expected for the MCU shortages, but it’s also been really nice to not have to even look at stock/lead times when considering/prototyping new products.

I wouldn't be surprised if keeping 180 days of high-running, common parts on hand becomes the norm for high-margin products.