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.
You can click off the park brake all you like, but if a door is still open, nothing will register on the ACARS. Logic for recording Off Blocks is "Doors Closed + Park Brake Released".
It's in fact far easier to Bend It Like Beckham
without ACARS. How many Virgin flights actually push at :20 but call it :15. Dozens? Hundreds?