Thanks for the input, all. The whole problem came about because of a very poorly planned itinerary, which involved checking the bag almost every single day, wasting time waiting for it at baggage claim over and over again, making lots of short connections that increased the likelihood that the bag would miss its connection, and having to haul a heavy rolling suitcase in some places not conducive to such.

I was finally able to get access/permission to modify the itinerary myself, and have cut it down to only 3 flights, 2 of which are direct. At this point, it would definitely be stupid to leave the bag in SYD and fight to check it on my layover. Thanks for pointing me in the right direction, and providing a little backing to the need to fix the itinerary.