Your title is not really the same as your question.  Assuming you are on a byte-based plan, it becomes a trade-off between how accurate a track do you want to send and how much data you want to use so I don't think there is a good answer on how to use it efficiently.  If you are asking what it is, the manual is a good place to start:

Tracking Settings

Send Interval

Sets the frequency at which the device records a track point and transmits it over the satellite network when you are moving.

Log Interval

Sets the frequency at which the device logs your location and updates the track line in memory.

Auto Track

Sets the device to start tracking when you turn on the device.

Ext. Tracking

Sets the device to enter sleep mode between track points to maximize battery life. Sleep mode disables Bluetooth^® wireless technology, detailed track lines, and message checking.

Stationary Interval

Sets the frequency at which the device records a track point and transmits it over the satellite network when you are not moving. This setting is only available for professional customers with a byte-based subscription plan.

Burst Tracking

When tracking, sets the device to create and send a detailed track line to provide the best approximation of your location. You can select the amount of data to use, and the device will create as many track points as possible. This setting is only available for professional customers with a byte-based subscription plan.