I've had quite a few "top" clubs going through managers on a massive level.
Man U and Liverpool have both had three or four managers in a season.
Once you are successful,or as successful as the board expect, then you can be manager for years (McLaren has been England manager for 20 years so far), but if the club isn't doing that well then some clubs can really rip through managers.
Definitely there aren't as many sackings generally, compared to real-life, but managers of clubs in financial trouble drop like flies.