The first assistant director is just so important that the choice of that person is critical to the movie.
So I've had really great assistant directors for my last seven movies.
The importance of the assistant director cannot be overemphasized.
Then I usually leave the choice of the second assistant director and any other assistant directors to the first assistant director, who will choose because he or she is responsible for the conduct and the efficiency of the second assistant directors.
The first assistant director runs the set. The whole mood of the movie, the whole tenor of the set comes off that person, and it's just a critical choice.