If your energy is finite (which is normally the case), the effect may also depend on the energy per shot you spend. A birdshot allows you to hit great many possible targets, but only very weakly. A buckshot hits fewer targets, but packs a bit more punch. A FMJ bullet shot from a sniper rifle allows you to hit an exact target with a great force, but you have to choose carefully.

What worked for me best was looking around a lot, identifying a few worthy targets, and aiming well.