VA schedules are like the weather in Melbourne. If you don't like it today, it will be different tomorrow.
I'm not sure why VA has the occasional additional mid day departure from LAX, VA6. It only operates one or two times a week (usually Wednesdays and always Saturdays as far as I can tell). It is accompanied by a late night departure from BNE VA9 to supply the next day's more typical late night LAX departure VA8.
I think the only reason they can do this is because they don't fly every day. On the days they have no flights scheduled, the next day they get going earlier. I can't be bothered to check, maybe the aircraft go on the MEL or SYD rotation on their 'off day', but if not they sit longer than the QF planes overall. In your case, there is no LAX-BNE on Jan 12th so the aircraft may even be sitting at LAX overnight, unless it is arriving from elsewhere.
If you don't want aircraft sitting at LAX, basically you need to double your flights
and your aircraft, or have an off-day like VA do. Because the flight round trip is over 24 hours.
Since flights are only profitable if there is demand, I would guess that doubling up on capacity from LAX-Australia isn't viable at the moment, especially if it involves a lot more aircraft in the fleet. So the LAX crowd get to see lots of cool Australian aircraft on their lunch break.
Enjoy VA, I quite enjoy their product, especially long-haul.