Time to dust off thoughts of getting towed out?
Actually, would there be any saving in starting one (or two, in a 3- or 4-holer) at push-back and then firing up the remainder closer to take-off?
Or, setting take-off sequence when a/c are still on the stand and only giving taki clearance when it's likely that the departures won't have to queue for ages (or at least dispersing around the field to free-up stands - I have in mind KJFK and the 60-min-plus evening rush waits, probably more than Australian fields)?
That is, it seems to me to be folly to give taxi clearance to, say, five departures in five minutes when there is at least a 1-min gap between take-offs; if all taxi out in a line, you are straight away looking at a 10-min delay for the last one off.