In addition to that good advice, Qantas is now closing its flights 30 minutes out too, and even if there is an available seat and you are 29 minutes before departure, you will be booked, penalty free on the next flight as a form of toilet training to make everyone aware of the new rule.
It happened to one of my colleagues last week, flying on a good Cityflyer fare.
That rule is probably long overdue, in fact, I think CX
has been doing this for ages, but the breaking point at the major airports is the chronic delays getting through security, meaning people get properly checked in and still miss the flights.
Jetstar's confiscatory rules in terms of the fare however are widely perceived to be a bloody minded rip-off, and I think they are a serious limitation on their acceptability to anyone who has to fly a lot in this country, never mind the crappy seat pitch and so forth, and last minute fares that are as dear as Qantas but with no meals included.
grumble, grumble, grumble