If your country has different CB broadcast channel for area, I will obliged if you inform me.
Currently this App works as below:
1. The main screen updates the as soon as the CB broadcast is received(or in next 2 seconds).
2. Widget: To save power the widget is refreshed after 30 minutes automatically. But any way the refresh can be done using the refresh button.
As you know these cell broadcasts totally depends on the network/mobile provider. So the frequency of update/ or even receiving the message is unpredictable.
Note: Working fine on Nexus 4 (4.4.2). As I don't have other devices, this doesn't guarantee to work specially below 4.0(ICS version).
Requesting not to rate negative if message not received because it may be the case the network operator doesn't support CB broadcast message.