The higher the magnification the lower the margin of error, or to put it another way the better you can resolve aiming errors.
That was pretty common knowledge when I was a kid. One of the old gun writers, Jack O'Connor perhaps or maybe he was quoting somebody else, wrote an article listing the potential error as you went from open sights to peep sights to low power scopes to higher power scopes. Like 1/2" for open sights, 1/4" for peep sights, then 1/8" for 4x and so on. Those are just for illustration, I completely forget the actual numbers but the progressive reduction in aiming error is what's important.
There is a reason bench rest shooters use 36x scopes or I think some go even higher, they want to get the lowest possible margin of aiming error. Now that said, you needn't go crazy, just use a little common sense and match the scope to the rifle's capability.
Fwiw, I have a 12x M8 Leupold that's 33 years old but it's tried and true, I'll generally mount it on new rifles to work up loads at 100 yards. That's enough magnification to let a good rifle and load shoot in the .2's which is about as good as I'll ever shoot anything.
