Hey, your welcome... But I did wanna add a little side bar to the repsonse I sent. And you may already know this...
It hit me that you wanna practice this way over a "clean" area. If you have the stock coil on or the big one, you will hear more signals - if there is more there - If there is no clean area you will have to "tighten" your swing pattern to pinpoint the target you want to dig... In essence it means a swing either way of 1-3 inches each way of center, or if the area is cleaner 1-8 inches each way until you narrow it down....
You ought to try to take either your probe, screw driver, pinpointer or digging tool out with your NON-DETECTING hand. Once you gather the primary signal, and in "one fell swoop" place it dead under the coil bolt when your in the testing, and then you will see the difference to where you are centering. You may see the coin is a 1/2" forward of the bolt like mine or 2 inches to the rear, but I doubt it will far from the from the bolt connection... Where ever you "find the Sweet Spot" on your coil center, just know that you should do all your coils for learning.
Practicing the hand eye coordination from the screen to the coil's designated area of "center" will help you a lot... When practicing on an open target like dropping a coin on a clean spot you will see what I mean...
In the pattern tightening issue I described above, you may wanna simulate, by using a target next to your coin to see what happens... But you have to make sure it falls in your descrimination pattern to hear it, If it doesn't and nulls out you may lose the primary target all together based on how close it may be, until you do tighten the swing pattern arc.
Hope it didn't confuse you, or tell you something you didn't know already, AND one more thing... It may help to add a bright "DOT" where the 'sweet spot' is on your coil to always look down at it and notice it quickly. It will also help you size the target while you are pinpointing, visually aiding your eye tracking to the ground . If you find that the sweet spot is right under the connector from the shaft to the coil then this is an unnecessary detail... Soon it will become second nature...
You can also learn to do this with the toe and heel of the coil the same way in some cases for pinpointing or narrowing down a target.
Asanaman