Because they don’t want to do anything to make brands not buy the spots during the episode.
So if an episode has product placement for pasta sauce A then pasta sauce B, C, and D don’t want to buy commercial spots for usually the entire run of the show.
It’s not set in stone but having it be that way for all your shows makes it easy to sell big blocks of commercial spots spread across the network.
Because they don’t want to do anything to make brands not buy the spots during the episode.
So if an episode has product placement for pasta sauce A then pasta sauce B, C, and D don’t want to buy commercial spots for usually the entire run of the show.
It’s not set in stone but having it be that way for all your shows makes it easy to sell big blocks of commercial spots spread across the network.