[hangonhn]

That's exactly it. She (and other managers on our engineering team) doesn't fire arbitrarily or on a whim. That's not what I meant by quick. The management culture is to always give frequent and timely feedback so that the person knows how they are performing -- be it good or bad. By the time they are fired, it's pretty obvious to them (and likely everyone else) that they're underperforming. It should never be a surprise to that person when it happens (or when the opposite happens such as when someone is promoted)

I think your question is a really good one and really gets to the nuances of having both a high performing team and psychologically safe place. It's much easier said than done and requires good, consistent management habits.