I've called on a client or two and worked with a station or two in more than 20 countries. I've never made a cume-based pitch and never seen a competitor make one, either.
In fact, in many countries where I have worked or currently work, there are ratings that don't even measure cume as they use coincidental or coincidental and same-day recall to measure.
Again, in 63 years in radio (and during 13 presidencies) I have never seen cume used. I suppose it happens, but so do total lunar eclipses... just not very often.
You are trying to make an abnormality into normalcy.
