Last time I checked, some airlines did use the A380 for 17-hour flights such as Dallas-Sydney and Dubai-Auckland. But other aircraft like B777-200LR, B787-9, A

Last time I checked, some airlines did use the A380 for 17-hour flights such as Dallas-Sydney and Dubai-Auckland. But other aircraft like B777-200LR, B787-9, A340 and A350 also have a similar (or even greater) range, so it will be more economical to use these smaller twinjets unless there's a lot of demand. Even if there is enough demand, it might make more business sense to offer four flights a week instead of two.