Its a great question to pose to the Forum, great Wintertime fodder for us ruminants to chew on...Like you said, its very subjective...Lets start there, and since I like to hear the sound of my own typing, I will offer some fuel to the campfire....
To 'GB frequently or not' is 'Subjective' in that theres just a ton of variables and target preferences on any given day....For a Megacladder, Who's primary focus is speedy recovery of shallow targets, a guy dont have to GB at all, except maybe in situations where the dirt determines, 'hey, you are into some old deep dirt here, so you might want to forget about scarfing up clad, and see what other targets are portending'...In these rare cases, I stop and consider, I take a minute and tighten up, set up right, and work the site optimumly...Other than that, a shallow fast target hunter has no need to GB at all! Just fire up and get with it!
That said, I have not GB'd my F70 at all in the past 5-6yrs...not done a 'factory reset' since I cant remember when...I just fire up and go with mid range settings and let the site determine how tight I gotta be..generally working the sens up or down according to the situation/day/weather/ground moisture content, etc..
I wanna know I got a good grip on any target 5" to surface, accurate location to hop coil and stab, composition and profile size..Gb is the least of my concerns, and my rig seems not to care either...
Now, theres folks otherwise inclined, and really want to know they are gaining the top echelon of the performance out of their rig, and I get that...I do the same thing with my car, I know and maintain my tire air pressure, my oil level, my diligence maintaining the MAF sensor, PVC valve to get the top MPG efficiency out of her....
So, one guy dont care a dink about his vehicle, driving on half flats and has no idea what a MAF sensor is and dont care about MPG or efficiency...but he GB's his detector religiously! And heres another guy who dont give a dink about GB'ing a detector, but knows exactly the details about the important operating systems in a car?
....They both get where they are going and they both will find some cool stuff! Its all about what trips a guy trigger!..Like you said, Subjective....