Not quite. Crews could easily do ADDIS-DUB-LAX-ADDIS Plenty of airlines send the crew only eastbound or westbound (or over the pole) to get home, e.g. ANZ1/2 via LHR to LAX, and I think the eastbound flight goes to Hong Kong?
Definitely not convinced.
Very approx timings: ADD-DUB about 9 hours, DUB-LAX about 12, LAX-DUB about 11 and DUB-ADD about 8, 2 hours on the ground at DUB in each direction.
So, two crews needed each way with a crew change at DUB.
NZ is LHR-LAX-AKL and vice versa, also needs 2 crews withn a change at LAX. LHR-HKG-AKL and v.v. is now scrapped.