As a relocation consultant in Melbourne, i have met 100's of property managers… There are a handful of very good ones!!.. The rest don't care.. A good agent should be available to show anyone your property that is interested within a short time of expressing interest.  These ridiculous open inspections for 15mins once a week don't work.. So if you have a property with an agent that is not renting, suggest you mystery call them and see how long it takes for someone to get back to you, let alone get out of their chair.
That's their job to lease your property asap..