 Because the show could make only a couple of location shoots in  Chicago each year, the exterior scenes would often have to be filmed  in advance of the rest of the episodes shoot back in LA. Sometimes  a scene for an episode would have to be shot before it was even  written. A famous example of this is the final scene in "Loves  Labor Lost," when Dr. Greene cries on the EL. Director  Mimi Leder (qv) could only give Anthony Edwards (qv) a brief  description of what was to occur and told him to "find it," "it"  being the sadness Greene was experiencing.