Routing between UK and eastern Oz one has to stop somewhere and an hour or few in such places as BKK and SIN are wasted whereas during a stop/connection in PER at least one can clear Oz customs & immigration thus arriving at their final destination as a domestic passenger able to clear their ultimate destination airport significantly quicker.
When I travelled to/from Oz on business many years ago it was 1 hour in BKK, then 2 hours in SYD before onwards to MEL, as we reached the hotel bar some of our aircrew workmates were trying to tempt me with a beer but I was too zombie-fied even for a beer.
By comparison I've done 14 hours, in economy, MNL to AMS, I was a smoker at the time but it was OK and once one has been airborne for that length of time another 3 hours ain't all that.
So would I prefer LHR/BKK/SYD/MEL (2 transit stops) or would I prefer LHR/PER/MEL (1 transit stop)? ... I'll take the latter option thanks!