The target is moving too fast to properly aim at so spraying bullets in its general direction is the viable option.
The best strategy is a single, well-placed shot. The best weapon is not determined by rate-of-fire, but by accuracy... Resulting in sniper rifles with a ridiculous amount of stabilizing gear and a scope that resembles nothing so much as the Hubble Space Telescope.
The best strategy is a single REALLY powerful shot that can punch through a planet but takes a long time to reload.
Subverted: The Hero sets aside the FN MAG and picks up a pistol, because he's only aiming at one mook.
Double Subverted: ...but then grabs the FN MAG when the other 20 mooks show up.
Defied: Soldiers are given strict orders to use a minimum amount of firepower.
Discussed: In training, the soldiers are told repeatedly "You aren't Rambo, so don't act like him!"
Conversed: "If real soldiers did that, they'd end up in jail"
Excessive firepower results in the death of allies and innocent bystanders.
An army's overuse of dakka quickly causes supply problems.
The hero's minigun spits out thousands of bullets a second, resulting in him running completely out of ammo in less than a minute, resulting in him up to his armpits in spent shells and leaving him wide open for the more conservative riflemen he's facing down.
Recoil sends the hero flying across the room, and he breaks his neck when he hits the wall.
Advanced targeting systems in the automated turrets ensure that only designated villains are targeted.
The army's enemies end up rapidly capitulating because of the sheer terror of getting shot at by them, though.
Because the minigun shoots so many bullets no enemies are left alive when the hero runs out of ammo.
The high-tech minigun has some kind of recoil dampening system.
Plotted A Good Waste: Both sides of the conflict use excessive amount of firepower to make a point about the horrors of war.
Played For Laughs: More dakka is used....while hunting rabbits.
Played For Drama: Excessive firepower is used by the mooks to give a greater sense of danger for the hero.