On the so called superlong and ultralong flights such as US and AU, its double crew, 2 cpts and 2 FOs. FOs always log only half the time, thats why I mentioned factorized in the post. For Cpts, they log all on one sector, being crew A, and half on the other sector.
Other routes, some 8-11 hours flight time, depending on the start of duty and some other factors, its 2 cpts and 1 FO. You then log 2/3. If only 2 pilots are needed on one sector and 3 on the other, one poor cpt deadheads on the sector (without being paied, an issue presently being adressed).
So on a typical roster as an FO, you may get some 100 hours flight time, but log only 60.
I dont know how long this practice will last though, as I heard in UAE its being fazed out. Pls someone correct me if I m wrong.