I've owned my eTRAC going on 5 years now and only once performed a Master (factory) reset for an intermittent problem which it didn't resolve...another story.
IMO, only do a master reset as a last resort to try an fix a problem. According to the Owners Manual, a Master reset will restore all settings to factory presets, erase all user modes and custom discrimination patterns.
Far as i can tell thats all it does. There's a remote possibility it might fix a problem related to stored user settings.
Remember there is also such a thing as a power-on reset with all modern electronics that utilize uProcessor circuitry.
Upon just turning on the device the power on reset will ;
start crystal oscillators which once in a great while don't start depending on the design, components, etc.,
reset the uProcessor(s) to a start state,
loads software from memory and executes it once the power on reset is completed,
and if applicable reset other chips to a start state.
In the case of the eTRAC, the power on reset will NOT erase any stored user data such as custom discrimination patterns, custom settings, etc.
Thats why just power cycling modern uProcessor electronic devices will usually fix a problem.