if your new you will have nicked the prop on the ground after the first flight and all the balancing that you did will be waisted.
generally I check the balance to make sure the prop is not totally out of wack, wood props tend to be close, plastic can be all over the place.
I have APC props that are perfect,and also so out that I wouldn't run it at all, it depends on each prop individually.
for the 46 sizes 10/6 to 12/4 on a trainer,for a plastic prop sand the heavy blade on the back side.
for wood a combo, sand a little, and clear coat the sanded area as well as the light side when dry, recheck-repeat.
when you get to larger props balance becomes extremely critical not only for the engine but the airframe the wear and tear from a out of balance prop can be fatal.