Such photo shoots require considerable situational awareness for several reasons:
Expensive gear all around.
Attention-attracting models.
Often being in less savory and/or remote areas in order to get "edgy" backgrounds (this particular location is better than it looks, which makes for a good location).
The tendancy of photographers to "zone out" and lose SA.
This image from yesterday's shoot shows a typical scenario. Note how the photographers are deep in concerntration with a gear bag a good distance behind them.

It so happened that I was not active, and I was observing in the area behind them. I noticed someone approaching as they sometimes due being that it's a public area, and I felt the need to keep and an eye on him and the unattended gear.
As he walked by I stood close to each bag as he passed and exhibited just enough body language to suggest "don't try anything". No direct eye contact or exchange of words took place, but knowing that I had my S&W 442 in my pocket helped me to feel quietly confident.
I've long felt that a "designated looker" is a good idea for events like this, but it's not always practical. And of course the looker being a CHL is a plus.