Modern manufactured steels have become state of the art. Strings are still being made the way they were 40 yrs. They can't take the constant stretching from the pedals over a long period, and still keep their sustain and tuning. When I lived in Detroit I kept strings on forever until they either broke or started to have that awful zinging sound. In the studio I change every 3 to 7 days.
Guitarists change generally every day.
Acoustic guitarists change for every 3 hr session. Sometimes they get a good set that lasts all day. That's how important strings are to the tuning and tonality of the instruments you hear on records. It's important to have a well tuned instrument. Any combination of these gauges have all been tried by the pro's and proven to be equally balanced for the best tone possible.