I send quite a lot of Express Post ( several a day, not on ebay) outside of the guarantee zone. Generally I find they arrive within 2 sometimes 3 business days. Very occasionally I have a doozy that takes regular speed but I would say it's 1/70 and I send quite a lot to regional areas a day or twos drive out of Perth for example.  I find the service very good and most economical regionally if P/O satchels are used ( I buy in lots of 100 and get 12.5% discount) . It is extremely rare for me to be positive about Aus Post but this service generally has served me well.  As per previous if its outside of the zone then you wont be getting any free satchels.