I had posted this on another schwinn thread about frame size. Tall frame in schwinn lightweights is the 23" frame size. In schwinn, my reference to "tall frame" is bikes before the early 60s. After that they expanded the frame size selection of the road bikes to many different sizes versus your standard 19", 21" and 23" (tall frame).
This whole section is devoted to cantilever tall frames (king size). Tall frames are much harder to find than the 19" and 21" frames. I run across 21" frame sizes all the time, sometimes 19" and almost never a 23" in 40s and 50s lightweights. My understanding of that is until the schwinn bike boom in the early to mid 60s (and more in the 70s) it was largely children and teens that rode bikes. A tall frame would have been for the rare tall adult riding the bike or tall kid / teen. Most rode the 21" frames. For paramounts / superiors those most likely were adults (cost and use case) and you would think you would see more large frames, but I don't see them and generally see 21". I don't know anything about road bikes or racing them but maybe the average size of person riding them is smaller (maybe has to do with body proportions / ratios that make a better more efficient rider...?) which would not require a larger frame. All that said, tall frames are just not as common.