As PIC you make the decision. Back when I trained for my PPL the communication rules were fairly proscribed. Things have changed, as they always will, and now we have virtually no communication system at all - its all up to the PIC to decide when & what to communicate (I amy be ovestating this a little, to make a point).
I friend of mine died just a month or so back, when two very experienced pilots did not to communicate (they also died). Perhaps if they monitored The Oaks frequency and or made a call or two, no one would have died that day.
I don't fly over hundreds of airfields, if I did I may be a little less enthusiastic about making the calls I do, who knows? For now I feel I am doing my bit to try and keep myself safe and those other pilots out there, who may not have made a call (cause they don't have to).
Here is an excellent example of what should happen, from this Forum, Landing Fees, KRviator;
"............................ when I went to Broken Hill.
"Dubbo Traffic Rex 6866 a Saab Taxiing for Broken Hill runway 05"
"Rex 6866 and Dubbo Traffic Alpha Bravo Charlie an RV 30 miles west maintaining 9,500 overhead time 20"
"Alpha Bravo Charlie, Rex 6866 we'll maintain 8,000 until we've confirmed we're past you"
"Rex 6866 much appreciated sir"
Shortly afterwards
"Alpha Bravo Charlie, Rex 6866 visual, your 11 o'clock low, 1 mile and we'll start our climb to the flight levels soon as we're past"
"Rex 6866, Alpha Bravo Charlie, copy sir, thank you"
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