Magnification range is mostly determined by choice of target. Intended range would be secondary for that issue.
If you are group shooting, more magnification is helpful. No real upper limit to what would help you other than practical considerations for the scope.
Steel and game at distance 10-15x is all you need.
Varminting can be a bit more magnification but anything over 25x has field of view and stabilization issues, at least in my experience.