I'm not sure of the frequency of their inspections. I have worked in local areas where track inspectors inspect it every second day, and then, depending on weather conditions, maybe every day.
My point was about slowing trains down. In that area, when we're working a night shift, there are fewer inspections at night, and these things happen like that. At minus 40, a rail can break fairly easily, and the track conditions aren't being inspected always...maybe daily, maybe twice a day, but not always.