Any mention NYC on this thread always causes ripples. Anyhow a relevant point highlighted by HH6702 is that the timings don't make sense on a untilisation basis unless program is not yet fully complete.
However it does mean one crew can do the out and back trip and have their required rest period in NYC.
Also from a utilisation point of view it is in the lull between summer timetable and Christmas/start of ski season. Utilisation is low anyway, and I doubt many routes could fill a B757 at that time of year; certainly not all the B757's Jet 2 have. Sending one to NYC will probably increase utilisation compared to what it would have been without these trips