It depends
Not all weapons have a burst mode. Often though, militaries prefer controlled bursts of full auto, but it depends on the role and weapons system. Machine gunners are more likely to go full hog than a rifleman for example, but that’s assuming that all soldiers do the most optimal choice in any given situation, which just isn’t true.
It’s a shame that they aren’t more popular; I didn’t really see prefectural flags flown that much outside of government buildings when I lived in Japan.