Chelsea management do not waste time on managers who fail to deliver that's one thing I admire in Chelsea owner Roman Abramovich.
Do you admire this? 
In my opinion, Abramovich is one of the top club owners that doesn't want to wait for a process, wants an instant result. Not all coaches can easily adapt or show their good achievement, some need time and process. Sir Alex Ferguson is one of the best examples, he needs 5 years to show his good achievement in Man United. In his early career as a Man United manager (coach), he even couldn't get a single EPL or UCL trophy. But he got all kinds of trophies, 5 years later.
Rebuilding process with the same manager at the helm is already a thing of the past since the league became so competitive that fans and board can't spend too much time waiting for silverware or positive results anymore. Maybe that impatience also comes with the generation.