Just depends on the month.
You tend to be rostered up to 84 credit hours (roughly translates to 84 block hours for an SO). So that translates into 3 longhaul patterns. There are shorter and longer patterns however and also reserve blocks of 6 days.
You can also (presently) choose a W pattern (double longhaul i.e. HKG-SFO-HKG-YVR say..) and then tend to get one W and one single trip.
It takes about 3.5 days to complete one longhaul say depart midnight Sunday land Wednesday morning.
There is plenty of possible variations though.
Good luck