For track use I've also heard that using air is better. The flexing of the tire when the pressure is lower allows the tire to build heat in the carcass. As the tire heats up, so does the air and the pressure increases. Hopefully when the tires are fully heated up, the air pressure is correct and your tires stick well and wear well.
I've heard when you run nitrogen you don't get as large a pressure increase. This means less flex in the tire initially so a longer amount of time to bring the carcass up to temperature.
If this were true, you'd want to use Nitrogen with tire warmers. Bring them to temperature, set and forget.
When we were using bias ply technology, yeah, lower pressure generated more heat through that bias ply weave of the carcass which resulted in a bigger increase in tire pressure. If tires got greasy, you increased your pressure to prevent so much carcass movement and heat. Racing at Brainerd, with no warm up lap and no tire warmers, it was no problem because your tires were warm before you got to turn one just because of the heat generated by the bias ply flex moving forward.
Radials generate heat through load. So, you have to corner with it, or brake and accelerate. If you don't load it up, it doesn't generate heat. Before tire warmers, you used the brakes a lot on the warm up lap in addition to being abrupt in cornering to try to generate any amount of heat before the start. Sun always works too.
On a radial, if you leave the pressure low, it has a bigger contact patch. More contact patch can generate more traction. But if it doesn't have heat, then it doesn't generate a lot of traction. So, often on a radial, increasing tire pressure will reduce the contact patch and generate load in a smaller contact patch. That load focused in a smaller patch will generate more heat that doing it the other way since the radial construction doesn't generate heat through simple carcass flex.
Nitrogen's biggest benefit is no water through humidity in the air that's being introduced into the tire, which expands and contracts in heat more dramatically than something like a "clean gas" as nitrogen.