Last week I flew ORD-SFO-ORD on UA and both outbound and inbound flights had a continuing flight that made no sense.
ORD-SFO was on 767 (very old one) that originated in IAD, but in SFO was going to LAS with the change of aircraft and crew. If someone was not going directly to LAS from ORD, the choice would make more sense would be to connect via DEN not SFO. The return flight from ORD was going to LGA, which made more sense, but even though both legs were on 757 it required an aircraft and gate change in ORD (B14 to C19) which makes no sense whatsoever. Why not send the same 757 all the way to LGA?
It seems like someone was tired on flight number assignment and decided to stick the same numbers on several flights that do not have much in common.