Yes, that would be after three written warnings. which of course could only come after several attempts at performance management after several transgressions in order to get to that stage.
Of course there needs to be due process when a person isn't performing according to their job descriptions. Just as there needs to be a process to assist people who experience a poor working environment. But just at the moment all we are doing is swinging the pendulum.
HVR, I should moderate my initial comment about your knowledge of Performance Management. Of course you do have knowledge of this (or I shouldn't have assumed you didn't) however, most of us here are not in large corporations, we are simply small businesses, employing maybe up to 30 people (total guess here).