Again, thanks for the replies! I guess the 'homogenization' I mentioned probably didn't occur until the mid '80s, if truly at all. My grandparents owned a number of portable/tabletop TV sets, all of which appeared to use 13" or 19" CRTs, though I never measured any of them. Their main TV for much of my youth was a 25" Sony Trinitron which eventually developed the usual weak reds and blues; they also had an early '70s 25"
Zenith Space Command console (chassis 25CC52) in the living room which had long fallen into disuse for some reason.
At home, we had an RCA 'ColorTrak' console from the early '80s, again with a 25" screen. We also had a couple of portable/tabletop sets, again likely a 19" or some such. In the kitchen was an Emerson radio/TV portable with a 5" color screen. I eventually acquired an RCA XL100 tabletop from 1978, likely with a 13" screen, which I found at a yard sale. So I've seen a few patterns over the years when it comes to screen size, though again, I never took measurements.
One reason I asked is because I happen to own an example of the first home video game system, the
Magnavox Odyssey, which used mylar overlays for several of its games. Two sets of overlays were included, a 'large' size for use with 23 and 25 inch televisions, and a 'medium' size for use with 18, 19, 20 and 21 inch TV sets, according to the
manual. I'll have to see how one of said overlays looks when placed in front of the screen on this Trinitron. For now, here's a picture of the Odyssey itself, along with its 'cartridges', cables and some of the accessories:
