Nolan has always been good at this, and it's never been as evident as in Oppenheimer, where he manages to capture the essence of the character, show his thoughts and compunctions, and not trip the boredom wires while doing so.
Capturing thought processes and revelations is a big hurdle that directors face. While the book can just narrate the thoughts of the subject, the same can't be done in movies — at least not without boring the audience. Nolan has always been good at this, and it's never been as evident as in Oppenheimer, where he manages to capture the essence of the character, show his thoughts and compunctions, and not trip the boredom wires while doing so.