We used to do MAN-BJL-MAN (Banjul, Gambia) which is 6 hours each way. Crewing used to roster us into discretion as a matter of course, until the CAA seen what was going on and said "hang on a minute, discretion isnt to be used like that"
The airline werent prepared to night stop crew in Banjul - who can blame them - so we now position crew on the aircraft and swap down route. (Dont forget the mozzy repellant)