Blimey that is insane. I don't think I could cope with that. You'd probably have got over the jet lag by the time you get to the airport to go home...
I think for four days I'd be willing to go up to 5/6 hours flight time - providing the flight times were good so you could actually enjoy most of that time there rather than two of the days basically just being travel days.
New York I have done a few times for 4 nights, not too bad to be honest, in fact we will probably go again next year..