All sensors are important. If one component gets too hot, you could lose a card or ports on a card. Clearly the sensors on your supervisor(s) are the most important. What you might consider doing instead of polling all sensors all the time, is rely on the device to send ciscoEnvMonTemperatureNotification (old) or ciscoEnvMonTempStatusChangeNotif (new) traps to alert you when the temperature becomes too high.
