Another, more recent, developement that compounds the problem is that often nowadays design and flight test are not in the same country let alone airfield. This can mean that not only is everything is filtered down a phone line - more possibility of misunderstanding and getting things wrong - but another group gets in on the process.
I find an increasing amount of my time is taken up explaining to a Project Engineer (a) the testing required (b) what is needed to accomplish that efficiently and finally (c) what the results mean & what we need to do about them. Good or bad Project guys can make or break programs and some of the arbitrary decisions made by them surpass all understanding.