I once did a corporate internal management course that was filled with pseudoscience bullshit. I imagine the impact of that course on the company's productivity was net negative. I'm sure lots of orgs have similar courses.

Learning styles have also been debunked for decades though they continue to be used in education. I saw an amusing line in an article that said 90% of teachers were happy to continue using them even after accepting they're nonsense.

And that's just theories that have been debunked (i.e. proven wrong).