Ok...I've got the F70 with 11"dd..heres how I do it...lets say you have a coin a few inches deep...hear the ping? raise the coil up higher and higher as you short swing it until the ping goes away, step to the side 90degrees, all the while swinging on that target, doing the same thing, gently swinging little short swings and raising and lowering the coil..bang, dead center of that middle spot on the coil...not even using the PP button. It just takes practice...probably 1000 targets really concentrating on what the modulated audio signal is telling you...this seems to work better running lower sens, like 55, the tones and strength of the target will tell you what it most likely is and how deep it is as well, very surprising how quickly attuned your ears become to subtle changes, coins on edge, stacks and spills, depth.. on coins in the 3" to surface range, you will get quick enough to go from ping to pouch in less than 10 seconds with your eyes closed. Why with your eyes closed? Because lots of times a fellow gets up early and wants to go hunting when its dark out, and lights only attract the wrong kind of attention. This is something you can practice out in your yard...I do use the PP button on deeper targets the same way...just holding it down while I short swing over the top of it, and settling in on the strongest signal.
Mud
Note: All this is done in one smooth fluid action, meaning after the first ping, short sweep two more pings as a guy is either moving the coil 90 degrees or stepping to the side, swinging all the while and at the same time bending down so on the last third ping, your screwdriver is already going into the ground, target is stabbed, hole is wowed out, and coin is captured and up you go...its as quick as a genuflect.