There was a brief, happy span of a couple decades without duck-n-cover or shooter drills, though.
I've lived near Camp David and Site R for 50+ years, so we always joked that if the missiles ever started flying, we'd be the first to know and go.
After 1991, the military aspects were stripped out, although in many schools they turned into an opt-in afterschool "patriot club" or some such. These were the primary source of videos like https://www.youtube.com/watch?v=LrxjYfl05ek.
Recently, they've announced that they'll be reviving the old Soviet format, so it'll become mandatory for all high schoolers again, beginning with the next school year (starting in September, 2023).
That said, I suspect these drills were more for theatre, like most of the TSA is now - put up a big visible show that you're doing _something_.
Reasonable people can disagree.
Too close? Incinerated. Doesn't matter.
Goldilocks nearby enough for glass shrapnel? Dodged some glass by being under desk! Win!
Far away? Heard a distant boom while under desk.
Hard to fault really.
Schools educate children to fit into society.
That was society at the time.