Maastricht UAC is BY FAR the most efficient
Back in the 90s, when it was possible to travel on the flight deck, I was on a business trip to Munich at the end of September (the meeting HAD to be held at that time, you must understand).
I was in the jump seat wearing a headset, somewhere high over the Netherlands, when I felt the need to ask the First Officer whether the headset was working. His response was to call "Speedbird 958, radio check". The ground responded "958, radio check". He then explained "Apart from Hello and Goodbye, that's all you ever hear on this frequency".