Some will remember....(Onya 'Traffic')...The 'Rules of the day'.
In the 'Designated Remote Areas', of which there were a couple, SARTIME with an EPIRB, was the minimum for PVT flights, Full Reporting - i.e.carriage of HF was the real requirement for every other flight, inc. VFR CHTR.
For 'obvious' reasons at the time /era. As has been stated, it did reduce the search area in the event of a mishap.
From memory, (So don't bite me head orf) The Central 'GAFA' was largely 'DRA', as was the Snowy area.
VFR / SARTIME Flights from Darwin to Alice were to be 'via highway'.
Pretty straightforward if nil HF. Carriage of HF meant you could plan to go 'anywhere'...
e.g. From Derby to Kununnura transitted the NW part of the large 'Central DRA', and we had to 'assist' on occasion, some 'East Coast' pilots doing their 'round OZ' trip sans HF and Sans ELT (As it was called at the time), to 'hire' an ELT from an obliging local to make them 'legal'.
(The rate was very reasonable.... so I'm led to believe...)
All necessary info was in the VFR Flight Guide of the time, with diagrams.....
However, some people just didn't read so it seems....
Cheers
p.s. Yes Dick, Mr Carson at Ceduna was a VERY obliging fellow.....