Of course there is the collary to all of this: The back-to-back flights.
Those involve
Mon: LHR-JFK/BOS/IAD
Tue: Back to LHR - Hotel near airport
Wed: LHR-JFK/BOS/IAD
Thurs: Back (sometimes even the morning daylight flight).
Messes up one's sleep patterns to no end.
Of course an LHR-SYD could net you 10 days away, with shuttle trips SIN/BKK-SYD/MEL in between.
Also, IIRC if the flight is over a certain lenght (10 hours comes to mind) the minimum rest period is two nights at the location.