Actually 'prime posting area' means most people want to go there, and you'll be bloody lucky if you get a job in the barossa.:) People who are there usually stay till they die or retire.
Lots of public servants who work there have been in their present jobs for decades. One woman I worked with has been living in Nurioopta and working at Modbury Heights for the last 15 years. She's finally won a job at Nuri High School.