As your experience builds the chance of launching un-hooked increases with each launch. Relying on your memory to do a hang check before each launch is flawed. Even check lists are flawed as they also rely on remembering to have it with you. Even if it is attached to your glider it will deteriorate over time.
The major place where memory falters is when you do actually remember to do your hang check, then you forget something, your camera, your water etc etc.
You unhook your harness to turn on your camera, get your water, then come back to your glider, launch conditions are stressful, you pick up your glider, you have the memory of doing your hang check right and suddenly find yourself launching unhooked.
The Aussie method eliminates your memory from the equation.
The Aussie Method attaches your harness to your glider during set-up and NEVER unhooks the harness until you have landed and are packing up, pretty simple really.
If you are on launch and forget something you climb out of your harness, your harness stays connected to your glider at all times.
This does not eliminate your hang check, a hang check needs to be done before every launch to catch other things like twisted lines, unlocked carabina etc.