It's actually more difficult than that. I don't know how it's done at Qlink, but assuming it's like mainline, they may not even have such an animal as a standby. Mainline longhaul uses them, but not shorthaul. They occupy a work day, and so increase the number of pilots that you need. Unless you have two or three per day, you don't have 24 hour coverage. From callout in Melbourne, to take off time in Bendigo, would be in the order of six hours. The person concerned will have had minimal sleep....and so would almost certainly be starting the duty already fatigued.