Originally Posted by
ugleeual
many times the longer layovers in Europe are due to limited service (not 7x a week) or a holiday period where the flights are reduced. The longer layovers in Asia are normally due to FAR rest requirements and augmentation as listed above.
^^^^
This
The long layover isn't good for anyone, the company included. I'll bet the pairings you're looking at don't involve daily service to the layover city.
SFO-SIN is about the only layover that I can think of with an extended FRMS/FAA mandated duration. Any others?