I can't see why you would monitor 126.7 when you are in a ctaf with a designated frequency.
If you intend landing at or departing from that AD, sure.
But if you are transiting a CTAF (or a bunch of them) you might want to keep monitoring 126.7 as well for situational awareness.
Bloggs: True. Actually the current AIP dated 17 AUG 2017 says:
ENR 1.1 - 75
10.1.4.2 Pilots of aircraft transiting in the vicinity of a non-controlled aerodrome should monitor the designated CTAF while within 10NM of the aerodrome.
It has change bars, so it may have changed then from the previous "in the vicinity of".
I am reminded of a statement that used to be frequently made by a prominent flyer in the Melbourne area when asked by any VFR broadcasting traffic to him and seeking a response:
"If you're VFR, keep your eyes open and your mouth shut".
Not particularly helpful and usually got a stunned silence.
It sounds like I'm going to need to add dual radios with dual frequency monitoring to my Christmas wish list for Santa so that I can fly safely in Australian skies.
Nah, it's called "frequency separation" by ATC.