FO runs depend on where you are based, up until recently the FOs were for the most part based in the hubs (HYA, BOS) and would be scheduled to fly on any number of routes, depending on passenger load. There are times when FOs are still required (inop autopilot in IFR, new CAs, etc) and we recently hired a substantial number of SICs who will be based in the outstations with the CAs so there is plenty of opportunity to log some time which can absolutely be logged; to put it simply it is a 2 crew operation, however we can substitute the FO with an autopilot which we routinely do.