Yep Peter, the longer the scale length, the tighter a given string will have to be to reach the same pitch. If you think about it in terms of playing and moving up frets to get higher pitched notes, it is quite clear.

The example you cite could be personal preference though. People vary a lot with strings as they do with choices of picks. There are limits beyond wich you could damage an instrument or have a string so sloppy it is horrible but there is room to manouvre and no real right or wrong.

I tend to think that once a person has some "ballpark" gauges, it is best for them to experiment from there to find what suits them best.