You’re talking about “field of view.”
A microscope’s field of view is the diameter of the circular area that appears when you look into a microscope. The higher magnification, the more detail you get because you focus your field of view onto a smaller area.
So, if you wish to study only one object (say, only one or two hairs), then higher magnification is better. But maybe you want to see the adjacent skin, or more hairs in the area. If so, you would have to use a lens with a larger field of vision and that means less magnification.
In the illustration, the smiley face is the hair. With less magnification, you see the hair, but also the surrounding skin. In the maximum magnification, you see the hair, but nothing adjacent. You have to pick the magnification you prefer … and, it’s not an easy matter.
A lot of your decision will depend on the type of hairs you prefer treating. If treating tiny upper lip hairs, then higher magnification. If you only do body hairs (that are already large) then probably less magnification so you can more quickly clear off the area by seeing a larger area. (I only use 3X magnification in a surgical telescope and only treat body hair).