i.e. if you are campaigning for Governor of NY, you can target New York state, but you can't target Manhattan, or Long Island, or men over 50, or people who liked the NRA.
Nearly everything else will generally only reach a subset of the voters, and that subset will have known demographic differences from the overall voter demographics for the jurisdiction.
Run an ad at in the 8-8:30 PM Sunday slot on every FOX TV station in a state, for example, and you'll get quite a different demographic than if you ran an ad on those same stations on Sunday afternoon. The first ad would be during "The Simpsons" and the second would probably be during an NFL football game.
I think things like hard cap campaign contribution limits (as in overall campaign fundraising cap rather than by donor type) could do more good to even the playing field. And it should reduce the web of "IOUs" that elected officials come into office with.
It is interesting to think of campaign efficiency (or propaganda efficiency lol) as CPV (cost per vote) to make it parallel to advertising metrics like CPC and CPI.