Hi Losh,
Sadly as much as it pains me to say, in this instance Trevor is somewhat correct in how to correctly adjust the handbrake by the "Genuine Holden Service Manual".
Technically if you have the 10 hole rotors (effectively a second set of wheel stud holes) you disconnect the handbrake cable from the threaded rod and adjust the shoes manually by using a flat bladed screwdriver to adjust each set of shoes via the star adjuster wheel thru those holes with the wheel off but the rotor still on and held in place by winding one of the wheel nuts on backwards to secure the rotor firmly in place to simulate it being at kerb weight.
Once you've done both sides you then re-attach the cable to the threaded rod to take up the slack within the cable.
Sadly it's a long winded way and as such most folks simply wind up the cable more on the threaded rod adjuster. It's a bit of a "6 of one, half a dozen of the other" situation. I've always done it via the handbrake lever adjustment rod (threaded) as it's the cable that stretches over time and not so much the shoes wearing that creates the slackness.
Also with not all vehicles having the 10 hole rotors and as is the case with your ute, it's just so much easier by simply adjusting it at the lever end of the system.
Check out the following link for the various rotors available for our VR~VS's
https://dba.com.au/products/catalogue/online-catalogue/
In the case of VR ute, look at this one which doesn't show any 10 hole rotors for utes while in VS they do as they found it to be a service advantage to have them.
https://dba.com.au/products/catalogue/online-catalogue/