My response is JUST for Prospecting mode:
I keep a little piece of paper in my pocket so I remember to hit each button in the correct sequence when I start out Prospecting for the day. Forgive me for sounding like I have a poor memory but for some reason, I wasn't doing it right when I first got the X-70 and this turned out to be my problem... I'd always hit one of the buttons in the wrong sequence during the procedure. This is what I do NOW each time I go out:
1/ Auto Noise Cancel
2/ Auto Ground Balance
3/ Turn On Ground Tracking
I re-do the Ground Balance when my area soil changes dramatically to be sure that I am in the best condition to detect. For example, if I'm detecting a road and then head down from loose gravel to thicker clays near water. The difference between the moist clay and the gravel road means that the detector should adjust if in Tracking Mode but tends to get held up if the transition involves LOTS of different factors - such as Moist/Dry/Clay/Gravel/Water/Ironstone/Bedrock-Basalt/Sandstone/Mud/Slate etc
If I don't do a rebalance in new areas, the Auto Ground Tracking doesn't always help me and I end up getting held up by hotrocks etc. If I dig and can't find the target, I tend to rebalance and then discover the soil had too much iron there. A rebalance for me will almost always cancel out this iron. Usually the Auto Ground Tracking does this well... but it does get fooled occasionally if multiple soil variants are processed quickly.
Taking a wander along similar ground (say: Sandstone in red-iron soil) means the occasional low-iron hot rocks are usually balanced out as you cover the ground. But if I take a drive or turn off the detector to walk a fair distance, when i turn it on again the new soil can confuse the detector and whilst it appears to operate normally, some false targets may show since the machine probably needs to be rebalanced. On one walk, I found just two hotrocks that were triggering the detector and yet I was surrounded by them. By balancing the detector properly, only the largest ironstone rocks triggered a false target signal.
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To answer your question more directly , I use the 'jump' method of bouncing the coil slightly when setting the Ground Balance because I feel it gives the coil a better average sampling of the soil below the surface... but it is very quick to lock on. Just a second or two.
When setting the Auto Noise Cancel, it's a 15 second process and i keep the coil perfectly still when auto-calibrating.