You may be on to something. It makes sense that the noise, confusion and tumult of thousands being herded vs. a maybe a couple hundred is more stressful for everyone, including the screeners who are exposed to it for an eight-hour shift.

However, in slow times the isolation of a deserted checkpoint can be dangerous for pax. My second-worst TSA experience was late at night; I'd been nearly last off the plane, found my luggage searched, damaged and things stolen, went back to the CP to get a complaint form (oh, those optimistic early days!). It's past midnight, six or eight screeners are the only people present. Basically I was screamed at and threatened with arrest for requesting (in a calm voice) a complaint form. One screener loudly announced to the one yelling at me his readiness to "be your witness if you need one for the arrest."

Fortunately, as arriving pax I had possession of all my stuff. Friend picking me up rang to find out why I was still in the terminal. Friend is an attorney. When the screeners realized I was getting real-time legal info from someone who'd called me they backed off, but I think it could have gone worse otherwise. They were like bored cats who'd suddenly found a mouse.