You know, it's less the fact that there are still uncalled seats 3 days after the vote, and more that the counting seems to be going at the pace of 2-3% per day. At this rate it's going to take two weeks to have final results.
You’re literally correct. Postal votes must be received within 13 days after polls close, then the weekend a fortnight after polling day is when they conduct the final distribution of preferences, with the results officially declared on the Monday through Wednesday the week after.
But if you think that’s bad the final declaration of Senate results isn’t until 4-5 weeks after polling day!
I seem to recall Australia's long count being used as an example by the 'No' campaign when the Lib-Dems forced a referendum to try and get rid of FPTP during the coalition years.