Tolerance of failure is different for ICs and Managers, partially because Managers tend to have such an ability to really screw things up in a way that isn't technical and has an impact on a bunch of other people in the company.
The shortest IC tenure I've seen here was the result of being a brilliant jerk (which interviewers did not catch during the interview cycle (and I speak here as one of the people who interviewed this person)). The shortest Manager tenure I've seen here was noticeably shorter than this, and was the result of pissing off your engineers.
I've not seen any IC here screw up on a technical level in such a way as to get fired for a first or even second screwup -- it really takes a pattern. My shortest IC termination was six months from hiring to termination.
