Im not sure about all over the world, but typically ADS-C is not used for radar operations, just non-radar. Because it is a contract, the hits come in at a much less rate then a radar sweep. Also, it relies entirely on satellite use, which can be unreliable at times. ADS-B on the other hand will be used to replace radar, as it gives a constant update to the track of the flight, through the use of ground and satellite services. Maybe someone is using contract as radar, but seems like your relying on a lot to get updates that quick, I would say it takes typically 30-45 seconds if not more to get a update when requested on an ADS-C aircraft.