So the issues here is 'common usage' vs Federal government usage vs State government usage. I don't know how we could do a survey, but when it comes to common usage, of course, this could vary by individual, so I believe 'common usage' should be low priority if there are recommended government standards. And if there are differences between state law and federal law, the recommendations of the federal government should trump state government since federal law tries to drive consistancy between states in a federation. The only potential exception is of course if the federal law explicitly states that Australian states must define their own terminology, at which point we need tz regions for each state. So therefore any survey should be based first only on federal government websites and statutes.