Hands up those who have been 'Rostered' to PX the likes of MAN-FRA-DXB-HKG-Min rest-PX MAA- RP MAA-FRA-PX MAN and then think that this is acceptable. This is an extremely debilitating pattern and is quite common. For those on the 777 the life style change/fatique issues coming your way you cannot comprehend until you have experienced them.
While I would occasionally be OK PXing on the Freighter a unilateral Yes or No I believe has to be voted as a NO.