Oh I’m well aware of that. But what if I’m in the DL terminal for the UAL callout then I still have to go through a different TSA checkpoint, hence not through security but still “legal”. What’s the point of being through security in one terminal if it’s no faster or worse still even slower than waiting somewhere outside security equidistant that you can pounce on any terminal. Just use common sense. This is all splitting hairs anyway, the chance you only have 20 mins in next to zero.
Obviously not all airports are like SFO. And The ready “pairing” is arguably different than a normal pairing since there is no plane to be at by D-35.