Disagree, a CBR-AKL or CBR-SIN flight does not need to be daily for it to be successful. They could probably even get away with a twice weekly service to SIN (on a B767 or a A330), but make it a Saturday service for leisure travelers and a Monday service for business travelers with it's SIN-CBR service on a Friday and a Sunday to suit timings of both groups of travelers with the plane overnighting in CBR, and there is nothing to stop a CBR-xSYD-SIN vv service to cover the other days of the week.
Of course choice of aircraft will be a big one. Lets say for example QF did the run, if you had a choice of a 20 year old B767 with main screen entertainment only (and no skybeds) for a direct CBR-SIN run, or you have a choice of a new A380 (with AVOD and skybeds) for a SYD-SIN run, I expect the direct CBR-SIN service would be a failure. That said, if the plane used for the service was at a similar level to the SYD-SIN options, then the service would probably work.