New York Avenue may be a dumping point for trains going straight into Brentwood Yard. A train at the end morning rush hour could go from Shady Grove or Grosvenor, dump whoever is left on the train at New York Avenue, and then head into the yard.
I'm surprised they took off DuPont Circle, they used it as a terminal last weekend.
Only once in my life have I seen a train use Friendship Heights as a terminal, circa 1997. During a major delay in service (one of the computers that controls the trains had crashed). A train going towards Shady Grove arrived and sat at Friendship Heights for quite awhile. After maybe 5 minutes of announcements saying the train would be held there momentarily, the operator came on and announced the train was being taken out of service. He pulled into the tunnel and after a few minutes, the lights on my side began to flash. A few minutes after that, the same train that had been going to Shady Grove came in signed for WHEATON, and we were on our way. It was also announced as the next train to serve stations between Friendship Heights and DuPont Circle, meaning some people still had to wait 10 minutes for a train and they would be standing once it arrived. All the seats were gone when we left Friendship Heights.