Um, yes, at least with regard to most programming on these stations.
There's essentially no prior screening; they don't have the personnel for it. It comes off the network, is often put on tape or in the server for broadcast later, and seldom does anyone at the station hear significant parts of it until it airs.
And maybe not even then <}B^)
“By these stations” I take it you mean Public Radio or most broadcast stations? And thanks for the reply, I really never thought that any public media would practice this.