CBS isn’t paying attention to live plus same day numbers or live plus three numbers anymore. As I mentioned before upthread, ViacomCBS is using other metrics that seeks to capture non broadcast audience viewership wh8ch in far more important.
As theschnauzer posted, most of the networks (including CBS) are both looking at data beyond what we the public see Broadcast metrics of Live, Live Same Day, Live plus 3, Live plus 7, or Live plus 30. All of them get data from Nielsen about streaming (though that is limited), and the various studios have also contracted out to various other metric gathering sites.
Now of course CBS (and all other broadcasters) haven't ever really used the Broadcast ratings that get published. For the most part they are publicity. The exception is and has always been product placement dollars. But ad rates (what have been the bread earner for most of broadcast history) is based on Commercial ratings. That information is almost never released (and never released in detail).
In reality while we track broadcast ratings, its basically just the most accurate way we the public have to judge how specific shows are doing. And as more and more of the viewing public use streaming as one of their primary ways of viewing media, that broadcast data gets less and less relevant as away to judge a shows performance.
Of course, because its really the only data we get to see, its still our best gauge to judge a shows performance. But it is less and less reliable. And its almost useless it making comparison between years.
Now ABC for example is at least releasing some of its MP ratings (Nielsens ratings that include some streaming, but nothing from mobile devices and not all services). So that we can see a show "A Million Little Things and Grey's Anatomy" make a huge leap in Multiplatform ratings far above the performance of other ABC shows that got the same Live ratings.
CBS is fairly stingy about that info and only seen a couple data points (Ghost primarily).
The biggest issue that the companies are having is that tracking streams is relatively easy. But that doesn't give you any information about whose watching. For example lets use Netflix. Netflix measures the minutes each stream is active, and the number of streams, and then reports that as hours watched. Which is fine. Its a subscription based service, so for the most part, they don't really care about whose watching. Now for example things like purchases of TAR on Amazon or iTunes are commercial free. So that's a relatively easy thing that can be tracked.
But for services that include an ad component that is where things get more difficult. The system Nielsen uses for the bulk of its data collection is designed for each audience member in the sample (which has ranged from 15,000 to 40,000 homes) to indicate every so many minutes that they are still watching (they also then have age, race, income and sex information from each person in their sample). Thats expensive, and a little unwieldy but ok for home use. The reason they haven't got it up for mobile is simple, they don't want to use the old style of trusting reporting data that you manual enter, but haven't yet come up with a great way to register you are watching on the go (or what do do when you share your mobile platform with someone outside of the sample). Other services have their own system, some with much better data especially for covering things Nielsen doesn't currently include, but their sample size has typically been smaller. And because the overall industry hasn't agreed to them, its more complicated in getting an ad buyer to take data that different from Nielsens. Some will some won't. As more and more data and the systems that collect it are vetted out, the bulk of the industry will start backing them in mass.