There were maybe 35 people on the nonstop SFO-JFK yesterday. Six in J and I think five in F. After a few glances into Y, I realized that some people must have been laying down in the row as more stood up when we landed.
Nonetheless, I overheard a couple FA talking about keeping MCE empty since no one has such reservations. Twice I saw the J FA escort someone from the exit row seats as I was in row 10 and was wondering why he dashed in the Y so quickly.