First remember this, not so long ago, TV station groups were limited to 12 stations. TV stations had little clout, and syndicators also had little clout, because of this.
Suppose MarkTV has 50 stations and in 40 of them "Two and A Half Men" will do well. It will tank in the other 10 markets where MarkTV has stations. Well I can get a rate because I have enough "clout." So I just air it in all 50 markets and take the loss in some, but overall it makes up for it.
Now just use this as a thought experiment and you can see why things today don't match up with yesteryear in a lot of ways.
I recall reading when Me-TV was still local, African American type reruns, "Good Times," "Sanford & Son," "The Jeffersons," "Amen" and so on were getting awesome numbers on the low power station. Now this makes sense, as WWME was a low power and limited to the city and near suburbs, over the air. African Americans have lower cable penetration.
I have a lot of black friends, and it would amuse me how their kids would rave to me how much they loved "JJ" and thought "Fred, Lamont and Aunt Ester" were so funny. I think it's odd they have no idea how dirty Redd could be. (And yes, I love Mr Foxx, he's what comics SHOULD be. They can be funny and clean and funny AND DIRTY, depending on their audience).
But a lot of localism dies. So when you think of over aired programs, try to remember, it may be more of a national/regional thing accounting for it.