One of the older family friends at home was a WW2 Marine veteran of the Pacific Island campaigns. Those guys never seemed to talk about combat, but they talked about things that happened in training or when R&R, in between campaigns/landings, etc.
He told me that one of the training classes they had was shooting from the hip with their M1 Garands while running a jungle trail. The rifle was loaded, they started off at a slow run with a grader/trainer behind them with a stop watch. They had to run the trail, shoot the "bad guys" on the run without putting their rifle on the shoulder/aiming it and reload as necessary. Targets/hits were scored after the run was completed. He told me that the corporal who graded/scored him made one comment, "bleep, son, I sure wouldn't want you shooting at me."
We never did anything like that in the Army (mid to late 70's). Not in basic, not in AIT and not once we got to our duty station/post. Now, during qualification we did (on some stages of fire) move forward towards the pop up targets and when we saw them we could decide whether to shoot standing, sitting/kneeling or prone based on distance and time limits. But we were stationary when we fired.
Once, at Ft. A.P. Hill, the E5 that ran the radio room got a 7.62 FMJ round into/through his butt pack, a couple inches behind the web belt. The guy to his right was moving forward with his M14 and the safety was off. He got too much "finger on the trigger" and let loose that one round. Six inches forward and the Sgt. would have take a round from hip to hip. I don't think they knew for sure who fired it as no rumor/name ever surfaced in spite of all the questions asked at the range and later back at the barracks. It may be fun, it's probably a skill more people should have, but it can be dangerous.