What is "Auto Interval" setting?
Starting v3.2, there's an "Auto Interval" option in phone software settings. When enabled, it'll automatically adjust the sending interval based on the speed: double the sending rate (half the sending interval value) when the speed is over 30 mph; double again when the speed is over 60 mph.
For example, your "Sending Interval" value is 1 minute, which means the phone reports its position every minute. When the phone is moving faster than 30 mph, the phone will report every 30 seconds (roughly. Acutual values varies on time used for GPS fix); when it's over 60 mph, the phone will report every 15 seconds (roughly).
The feature is useful on highway driving as it adds more sampling points.