Non-written rules developed by Christopher Nolan made his other films even better.
Though his Batman trilogy is legendary, Christopher Nolan is a great Director in other respects as well. He followed a secret guideline while creating those films that genuinely improved his other projects!
Christopher Nolan Never Did Two Batman Back-To- Back Movies
Usually making a movie, most directors start working on the next one right away. neither Christopher Nolan. He made sure to pause from the Batman universe to create quite different films between every Batman release. He thus produced "The Prestige" following "Batman Begins". Later, following "The Dark Knight," he created "Inception".
Though it seems like a small decision, his work was much affected by this one. He made sure to investigate several genres since he wanted to avoid being limited to only superhero films. This reveals his love of movies and his inclination toward trying novel ideas.
Why did Nolan find great success making original movies between the dark knight ones?
According to Nolan, his other projects and Batman movies actually benefited one another. Making one kind of film helped him develop as a Director and pick fresh ideas he could then apply on his next projects. Thus, Batman's work got even better when he alternated between him and other kinds of films.
Had he not done this, perhaps his films would not be as good as they are. It also prevented him from coming to be known as simply a superhero director. He wanted to be known as a flexible director, and he most definitely reached that mark!