They can go full gear. The only complaint I've ever reilably given concerns "soldiers stares", pheromone exchanges, standards of realism, and basic addictive personalities.
In such surroundings as active fire fight, a soldier is conditioning their brain's wiring of the moment. With fair predictable endorphin creation from pheromones, a male and female are wiring their brains to, "stay alive with this opaite".