I think there are several issues here, domestic vs international, different airport layouts and secuity areas, security consistence.
the other thread re security confiscations comes here as well esp with consistency. My wife can be on the same trip, wearing same clothes and not trip metal detactor at one airport, but trigger at another. Obviously the alarm tolerance can be different at different airports to trigger alarms. This can cause delays.
Domestically at Brisbane, after checking in, the security area is very close. If you had to produce id to get tickets, you may still have change from the cab in your pockets, car keys from parking. If your like me, I like to know that I have my wallet, keys, sunnies etc still on me, bit ocd. The security you have to put bag up, get laptop out, find another tray for keys,wallet,sunnies, change etc. i do this the quickest i can. I like to wait and see the items start to go through, to prevent theft, then walk through detector. Then get other end and have to get organised again, with pretty much nowhere to do this before the escalator. Trying to avoid the explosive test making sure wife and i have everything.
Internationally at brisbane, we can be more organised, i put all my belongings temp in cabin bag, except for passport, and there is room to do this, before going down stairs, as usually will have to take shoes and belt off before secuirty after filling in departure card.
So in essence, brisbane domestic departure dont have an seperate area to get organsed before security, after checking in and bag drop., ie a table or rack etc
International departure much easy to get organised upstairs, plenty of area with places to do this, before going down stairs.
As for jumping queue that can be problematic, as a couple I want to try to have one go through to start to collect things, the other then goes through maaking sure everything went through to assist, if someone puts gear in between a couples bags and trays can be issue, at the other end.