BMW's services are not set at 25K kms, they are driver dependent. I've had 5 BMWs and never reached that distance between services, lowest was 17K Kim's on a E46 328i ..... Lowest my dealer had ever seen .....
South Africa has a similar climate to Australia, with more extreme temps, summer heat to 50degrees C in places and winter temps of lower than -10degrees C.
Problem is not the schedule, it's the requirements of the later 6cylinder engines needing really good oil or the Vanos packs up within 100K kms and it does that even in Germany. Blame the previous owners.... I had an E36 M3 for 160K kms with no issues due to regular full
synthetic oil changes.