Correct read-back acknowledgements of verbal instructions has stood the test of time. Where it falls down is when gash replies are made, such as “Yeah, we can do that”, or no reply at all. Too often I have heard this on the airwaves over a certain large continent. There sometimes seems to be a competition to out-gash other users.
Contrast that with the London FIR, which was always a joy after a long night’s slog.
Mog