They didn't fire many people quickly, but it had a deeply chilling effect when someone was only at the company for a month or two before disappearing.
One of the unspoken difficulties of firing fast is that the person does a lot of relationship building with people who don't work with their output. It was often the case that someone would become well-liked by people who never saw their code, who would then become distraught when the likable person vanished one day.
