The 24 hour rule is definitely used by Qantas. One good example of this I did was SYD-CHC arriving around noon, had the afternoon and evening in CHC then flew down to Queenstown the next morning without using up a stopover.
A single booking of PER-SYD (1)-New Zealand(2)-MEL(3)-PER would have had 3 stopovers, and cost 50+10+10=70k points.
By splitting it into an Australian PER-SYD-Open Jaw-MEL-PER and an internation leg of SYD-New Zealand-MEL-"open jaw return to Syd, but didn't actually travel that" it was only 60k.
Still wasn't as good as our 45k points for round Aus in J class that we did for our honeymoon, you could have 5 stopovers back then... PER-MEL-LST(1)-open jaw-HBA-MEL(2)-BNE(3)-MKY(4)-SYD(5)-PER. Fabulous! To think it was the same points for a straight PER-MEL-PER flight!