I’ve fired people “on the spot” probably 5-6 times in my career.

In half the cases, it was for truly inappropriate conduct. Hopefully, I don’t have to explain why that was. Zero tolerance means zero tolerance.

The more relevant times, it’s been because what they were doing was so damaging to the company that I just needed them out. Immediately. I think this is what Tim Armstrong was trying to do, albeit very poorly.

In one case, my first time as a new CEO, I had a unique engineer that was so critical to our technology he was truly irreplaceable. And he took advantage of that constantly, leveraging it in ways that the rest of the company could barely tolerate. Finally, in one meeting, he so challenged my authority and undermined our mission that I just had to walk him out of the meeting, and fire him on the spot (although not in front of anyone). We found a way to survive without his irreplaceable skills when the alternative was such a literally toxic work environment that failure would be certain.

Another time, I had a poor performing VP that “quit.” Apparently, though, he half changed his mind that night and came into work the next morning early, and called a team meeting for his whole team. That was a little too late. I had to walk into his team meeting (it wasn’t his team anymore), pull him out, and walk him out.

And in all these cases, especially the second category, it was my fault. I’d hired them, or approved their hiring. Blame yourself first for a bad senior hire. You let them in the door.

This question originally appeared on Quora: How do so many CEOs fire people on the spot without any apparent consequence?