Oz doesn't always require an alternate providing the destination met. forecast is above certain defined limits within a certain period bracketing your ETA. It's quite possible to depart with the destination below those limits - requiring an alternate - and arrive with the destination above the limits - removing the need for the alternate.
One of the variations on this theme is for the met. to be forecast to improve above the limit by a certain time. It's always been possible to plan to hold until the operational requirement ceases however it may require too much fuel/time etc.
You arrive before that time, intending to divert, then reassess fuel vs holding until the operational requirement ceases. Quite do-able.