This screen is based off the Oneview Collector intervals which my default is 15 minutes.
the device view is 1 minute, and is in alignment with your concerns. Sometimes the best method to get information about device down is Alarms Manager email notifications configured. The other alternative is to get the Collector engine configured for 5 minute intervals. This may increase CPU usage somewhat on the server, but is an option.
If you are using maps, they are polled at 30 second intervals.