As an otr driver for some years I never let my truck idle except to air up the brakes. I also had a buzzer that would alert me to low air pressure. I did idle for a few minute, about 3 was long enough, to cool the turbo. Ask any driver how long they let their rig idle before they move. If not letting it get up to temp before they leave has hurt their engine. I guarantee they would not leave if they were facing any damage to the engine. As we know they only make money if the wheels are turning. They will not do anything that will damage their engine.