You've made this point before and it seems like a good one, but it raises a question. If you don't have a trial period, does that not make it harder to correct mistakes? The barrier to quickly firing someone who (perhaps through no fault of their own) turns out to have been a bad choice is surely higher than allowing a trial to expire or whatnot.

Since bad hires are one of the worst things that can happen and no one is perfect at hiring, I'm curious what you do about this problem. Do you just work harder at getting closer to perfect?

It seems to me that there's always an implicit trial period anyway—the question is how you encode it. The best people, who have many options, won't want to stick around if they made a mistake either, right?