The only time I have ever needed to scale up an environment sphere is when either dealing with very large objects, such as a full scale Titanic in this image (at 890 feet, it was a bit hard to make it look good in a sphere with a radius of 750 feet, lol), or when dealing with animation involving great distances, such as a jumbo jet flying into the distance. If the animation is long enough, or the speed is great enough, the object will eventually leave the sphere. Other than that, there is not reason to scale up spheres. (or scale them down, for that matter)

Your specialist military, sci-fi, historical and real world site.