It shouldn’t really be.
Certain periods are called ‘sweeps’ because that’s when the audience levels for each show are measured by Neilsen. Based upon those numbers the networks can set their advertising prices for the coming months.
The problem is that it’s antiquainted. The date back from a time when it just wasn’t possible to keep track of ratings in real time. Used to be each Neilsen family kept a written log of which programs were being watched in each house and they’d mail that in after the ratings period was over.
That’s now foolish, let’s face it. It led to (and still does) the networks and local news shows loading up with good stuff (or tittilating stuff, even worse) only during that period and then reverting to crap the other times.
Nowadays it wouldn’t even be difficult to track real-time ratings. And, IIRC, the ratings are now being gathered electronically so they’re halfway there.
Of course, if they did that there wouldn’t be this big media hype about sweeps every now and again.
Television wimps. I have to prove my magazines have the right circulation every damn issue.