I'm not an cliometrician, but my impression is that it took about 4 decades for electricity and steam to do much for productivity.

And it was in 1987 that Nobel laureate economist Robert Solow famously said “You can see the computer age everywhere but in the productivity statistics”

I mean, maybe AI will be faster, because it's especially easy to apply compared to generally applicable technologies. There was the Bank of Korea study showing this spring that did show productivity gains with single proprietors--folks who don't have to reorg employees and processes to do something with more abilty or saved time.

But, generally, I don't know that there was an reason to expect that corporate America generally was going to see an AI payoff so soon.