In my opinion, it all depends on the ground conditions. Hard to find two places that are the same.
I usually show up and start swinging and see what I find. If something seems off, tweak a setting or two until signals start popping.
You hear lots of stories of guys finding the best things on the walk back to the car... probably because it takes that long to get familiar with the place and tune the detector based on a little time there.
Say you found a hot spot and save your settings for the next trip back... chances are the ground will be different next time. Maybe drier dirt or wet if it rained.
First half hour or so is spent analyzing the ground in my history of detecting.
Hope this helps.
This man has a plan areas I hunt frequently I have a dime buried at 8 inches at all my sites and adjust my detector on the response I receive from it speeds up the adjustment process . some days it bangs loud and clear other days hard to hear ground emi change daily .
Rattelhead I have no doubt what you see is true but I have never received a signal in fast that would make me miss a target because of unstable #s . Just saying unstable tid as long as there in the coin range are going to get dug .
People ask this ? all the time and rely on what others say which is wrong all you have to do is sweep a 8 inch target in your ground .Using deep, fast ,deep and fast , or neither one checked and see which one gives the best signal .But if no difference I would be running fast .
Ground has more to do with it than you think every buddy takes it for granted that auto ground balance will adjust to the perfect balance every time as we move along however the ground can change from mild to harsh very quickly and auto is not going to keep up and you will loose depth . Now auto sensitivity changes to compensate for more ground noise it go's lower so your loosing depth however in manual you stay at the level you choose just got to slow down . That's why they have manual ground balance which give you perfect balance for the spot you balanced on .As you move along in manual ground balance the ground changes again you can hear the threshold change time to ground balance again but where there's targets every where go back to that clear spot you balance before won't work where your at now.
So that's why people run auto but when you hit that harsher ground you can't hear it in auto (threshold change ) the only thing you hear is more ground noise, ground balance disc out ground noise from real target's separating the two.
So if your in auto slow down the machine has to disc out more ground noise the harsher the ground is so look at it this way the more ground noise the slower the sweep give ground balance a chance to disc out the ground noise or suffer loss of depth without knowing it .sube