From how I understand it, the concentric coil throws an inverted 'cone' shaped signal, so without using your pinpoint, and focusing your eyes on the ground where the ping is coming from, as you tightly quick swing (wiggle) the coil all the while raising it progressively higher off the target, that ping should be dead under at the end of the 'cone'...As you raise the coil, the audio strength will tell you how deep it is too, what size it is, etc...
I think folks call this method the "minelab wiggle"...
You practice using your eyes on the ground for location, and your ears to recognize the strength (depth)...
A DD coil throws sort of a long Wedge shaped signal, but this discipline also works with it...raising and swinging (or hopping) at the same time, listening to the signal strength and looking at the dirt (not the screen) for where the target is....I do not know if the (hop coil) works with a concentric...it works with the DD very much nicely!
After a while, you wont look at the screen at all except on initial set up and check battery level...Since the 70 saves the former program used, and the battery life is @ a half century, a guy can turn it on and off hundreds of times while smoke jumping from park to park and never once look at the screen for weeks...
So think of an inverted cone, and also listen for the audio strength as you raise and wiggle that coil over a target...focus your eyes on the spot, stab a screwdriver down into the ground on the target and at the depth you think the target is...then excavate and see how close you are!

You will quickly either nail the coin on the first stab with the driver, or be within a golfball sized area all the time...
Mud