All Strips sensors have been optimized for long battery life time. This is achieved by minimizing the time that the unit is active and the frequency it communicates with the gateway.
At an event, (open/closing of a window or door) Strips wakes up and sends a message to the gateway and directly goes back to standby mode once the acknowledgement from the gateway is received (one blink).
In the case when a routing device is used to extend the range, the message is first received by the routing device and then passed on to the gateway. This leads to the sensor needing to stay active for a longer period of time which leads to more power being used which may affect the overall battery lifetime. Extra battery effort is required for this instead of when the sensor is communicating directly to the gateway.