A good way of knowing how complex something is going to be, is to look at the number of variables and how much of an impact those variables have.
This is probably the number one reason why designing high performing and resilient systems is difficult. However, once you understand the variables, it gets somewhat easier.
But what do you do if you are handling multiple such systems at the same time? Because that is what leaders are expected to do with the people they lead.
Every person comes in with their own set of goals, fears, trauma, beliefs and experiences. And all these things are subject to change rather quickly and silently.
So if you are part of a team whose leader has done a good job, know that it wouldn't have been easy for them. And, whenever possible, let them know that you appreciate them.
After all, leaders are people too.