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I'm not sure how seriously to take this research but Nielsen survey data appears to indicate 6-10 AM and 3-7 PM (i.e. morning and afternoon drive) are not the periods when most people are listening to traditional radio. According to the research, it's actually middays (10 AM-3 PM) when people are at work or at home - but not necessarily on the road.
Think Most AM/FM Listening Happens In Drive Time? Think Again
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Drive times have far more listeners, but the time spent listening at midday pushes is over for hours tuned.