Just a few quick points of clarification.
Watch Virgins OTP sky rocket when it get ACARS and click off the park brake with one minute to go to pushback within 15 mins like Qantas often do.
In order for us to release the park brake, we need to be locked up, ready to push and essentially be waiting for an ATC clearance to push back. As a rule, QF pilots don't arbitrarily release the park brake to tick the box. Quite the opposite in fact, releasing the brake early covers for other areas who may have stuffed something up. If we release the park brake early those issues are never fixed.
I'd be stunned if DJ didn't work the system the same way when they get ACARS. It'll need something other than what you suggest for the OTP figures to change.
Watch that number come a lot closer when Virgin get more gate room in Sydney and Perth.
Yes, more gate space would be a great thing and not just for DJ. Certainly there are times these days when gate space for QF services is an issue- particularly in MEL, SYD and PER. Of course, the Sydney movement cap occasionally doesn't help (all carriers) with the apron congestion it causes.