If I recall the Ayoob narrative, one of the officers in the Newhall Tragedy had already been wounded, and was trying to reload his revolver, while crouched behind his vehicle. Range training in those days required officers to empty the brass into their hand, then shove the empties into tight pants pockets............so the range wasn't covered in spent brass. The officer should have dumped his spent cases on the ground to allow a faster reload, but he followed his training, and was trying to put the brass in his pocket when the bad guy outflanked him and shot him in the head.

Range rules changed soon after.

When I was a rookie in the early 80's, we trained at a private range owned by the city in a remote area. All stages with revolvers and shotguns involved firing until empty, then re-holstering empty guns and changing targets. It finally dawned on our supervisor that if someone with a grudge popped up unannounced and opened fire as soon as we stopped shooting, NO one there would be able to return fire. Speedloaders replaced dump pouches almost immediately.

Range rules changed soon after. Thankfully, before someone got killed over bad policy.