well, being a postie myself, the problem is usually the aussie post criteria, not the postie.
when you rock up in the morning you have your mail counted, they then give you a time sheet in what time
your expected to finish sorting the mail and what time you get it all delivered.
so for example, I start 6am, I do just one street in the city.
usually i'm finished sorting around 9am and they'll give me a stupid time like, be back at 11.24
based on my mail that day, but they don't know how many regies i have, so if i got 15 regies, i have to deliver to get signed.
sometimes i can stuff around for 10 minutes for one letter, waiting for some knob to get out of the shower or something, add it all up and my times are totally stuffed, you then get pressured to explain why you got back 32 minutes later then the computer calculated, and believe me, some posties almost get suicidel from the pressure.
also there can be many other reasons, like if the package is a bit too big and should of been delivered as a parcel in a van, posties can't carry it so instead of sending it back through the system, they will write a card and have it delivered to your local post shop.
oh, another crappy thing now days is aussie post delivers junk mail, which also doesn't get counted that well.
so instead of delivering to just houses with letters, you need to hit every single house just to put in junk mail.
I'd imagine your postie is under pressure to deliver on time, give him a break hey.