Usually the airlines cabin crew prefer to take a sit if not on duty. Have you ever think about how their work is hard? Generally an aircraft has about 250-300 (or more) seats. However, the crew number is around 10-16 (depends on the aircraft and airlines policy). So, the ratio between flight attendant and passenger could be 1:25 - 1:30 or it can be more. If it is a long haul flight, they should "KEEP WALKING" to other country for 12+ hours. Do not think that a flight attendant job is so easy!