I attached the Hi-Freq DD coil just to test it out (about 2 weeks after I got the Xterra) and haven't taken it off since. To me the DD coil is like using a sharp long flat blade to scan with (perpendicular to the ground) so it is easy to separate trash and damn easy to pinpoint.
Find the target, scan it a couple of times to 'narrow down' the location, press pinpoint, lock it in and then pull back towards you. When the signal stops, your target is at the nose of the coil. Easy.