Absolutely Nigel, that would work... if the big aeroplanes were available at the times you wanted them... if the crew were available to fly them... if the bays were available at the Domestic terminals to cope with the bigger aeroplanes... if pax were happy going through the International terminal (and all the hullabaloo and extra time that entails) because that's the only place with the facilities for the A380...
Theoretically it makes sense, but the practicalities of actually making it work make life more complicated. Having said that, I'm not sure how the majors cycle their aircraft around so I don't know how complicated or otherwise it potentially could be to slot a cheeky Melbourne return in somewhere. But from my perspective the more complicated a situation is - with different aeroplanes and crew coming from everywhere at all different times - the harder it is to sort out when something (inevitably) goes wrong somewhere. A fleet made up of a single type is far simpler to re-arrange if required!
