In the early '90's, decades before "balanced" became a catch-word, I didn't like the feel of the middle strings, D-65 and A-85, on the standard set of 45-105 Boomers. Too tight. So I did the math, and realized that, given the same or similar construction from string to string, that the 60 and 80 might feel more like the 45 and 105. It did.
Right about the same time, GHS introduced its then-new string, the Progressives, with the "52" alloy that had more iron, less nickel in the wrap alloy. That also fixed the tendency of my low E string to thump prematurely, since my hand perspiration tends to eat nickel.
I asked if they could be ordered in singles, which they could, and so for over two decades I have been ordering "balanced" 45-60-80-105 GHS Progressive Singles for my Rickenbacker 4002 (that's right - "2," not "1" or "3").
Now, "everybody" has a tension chart so you can compare. And after all these years, the numbers bear out what the strings felt like then and now.