...I've been following this thread for a few days now and I'd like to chip in a couple of thoughts from personal experience....
In any busy ATC sector (..anywhere) some simple human factors should be taken into consideration:
ATCers subjected to continuous traffic demand tend to become irritable. The traffic saturation level differs from person to person, but it takes only one additional pilot (with a perfectly reasonable request sometimes..) to trigger the effect and from that moment R/T resembles a tug-o-war for frequency time.
In such a situation pilots should try to avoid unnecessary requests (eg. shortcuts) until frequency becomes again desaturated.
Another good practice is after changing frequency to another sector to monitor for a few seconds before transmitting, to avoid stepping onto someone else's transmission...
...frequency time can become a very precious and rare commodity.
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...time danaos et dona ferentes