Diego Simeone has been managing Athletico Madrid for nearly 700 or so games if I am not wrong, which is quite a lot and something we do not see that often anymore, because most teams just change their managers like they are changing a sock so we do not get to see this many teams with the same manager all that often.
A coach staying very long in a team is good but there ought to be a limit that will based on the achievements of the coach and the progress they gave made as well. To me a good coach should be able to prove himself within a period of five years. Diego Semeone is a good coach no doubt, but the results he has achieved in Atletico Madrid, in my opinion, is less than expectations and the name of Atletico Madrid. I remember he has lost Champions league final about twice which is 2014 and 2016. This to me is not a good one and if I were to be the management of the club, I would have tried another coach.
If a new manager is appointed in a club and he is removed from the team in the next season, then we say that the manager should be given more time because a manager cannot fully apply his skills in one season. But if a manager takes charge of the same team for five consecutive seasons and cannot bring significant changes in the performance of that team, then the club should exclude that manager and plan anew. A manager who has not done well for the team in five years will not do well in the future. We may have forgotten the last time Atlético Madrid performed to our liking. They are not seen to perform significantly in either the Champions League or La Liga. I would definitely support a change of manager if their club's performance changes by changing the manager.