EMB and Muffin
I was strike three - I feel better now - when I did my original reply above it was far more detailed but it cradhed also, thus the crack the sads with the system much briefer one as you too EMB.
In an unqualified legal sense, I would argue that the average pilot would win a case based on conformance with the NAS 2C material and the current AIP. I suggest the Court would find the pilot had acted within the bounds of the reasonable man and particularly as the CTAF is defined as a procedure with NO physical boundary.
But in the ultimate, and common sense, if you look at the analyses of MTAF and MBZ matters you may find they were a safety shield 'in the mind'. The brain thinks at its speed = time to analyse and decide, therefore the NAS concept of giving calls at an appropriate distance (not too far or too often) is good commonsense. Where NAS goes astray is too many circuit calls, and in a training environment the intentions call on final is too late - you need to know on the base turn if its a full stop or T&G to establish the correct separation.
I also believe that the VFR pilot training package (which has a little IF flying to ensure one learns about vertigo
) should have a section later in the training (at NAVEX stage) where one learns a little about IFR procedures at CTAF to comprehend the workload and approach basics. This would greatly assist ensuring separation. I have put this suggestion to CASA.