Very true. But the video/audio recordings don't show any pause between the first shot and the next four. If the shooter took a moment to assess if the first shot was on target there would have been a slight reaction time pause before the second shot.

That all five shots came in a bunch with no pause seems to indicate the shooter intended rapid fire from the beginning. If so, that in turn indicates the shooter didn't squeeze off that first round in top form, because when you do that the exact time the first shot is released is almost a surprise in the zen-like continuity and evenness of squeezing off the shot.

I'm not saying the first shot isn't likely to be the most unhurried, I'm just saying that when you intend five shots in rapid fire from the first one on it's very difficult not to rush the squeeze off of the first shot just a bit, giving it just the slightest jerk to it instead of a really smooth and even squeeze.

The US is very lucky the shooter was not a professional.