I’ve got one cop video which shows the difference between aimed shots and spray/pray techniques and it’s pretty dramatic. From forty yards away firing a FAL rifle on full auto at four or five adversaries produced no hits which would produce major injuries while emptying the mag; four or five aimed shots produced kill shots on all adversaries while taking no more time. The impression I get is that full auto shooting should only be done with belt-fed weapons and you’re basically fighting WW-I when you do it even with the belt-fed weapons. The situation which calls for it rarely exists any more.
Then there is the classic example of the Rhodesian military in the 70s, which had select fire FALs. Due to ammo constraints, their armorers converted all of the military's rifles to semi-only, and their "kills" went up dramatically!
Then why does the military issue M-249s and M-240s? Many militaries are still using full auto capable weapons as the basic infantry rifle as well. Even some which use very modern M-16s. Sometimes you really need suppressive fire.