When I first started I was told by Sandman and others who have sued the Excal to always check a null by sweeping a null from a different angle 90 degrees from the original sweep (north to south is first sweep, then 2nd sweep is east to west). One day while hunting I got a null and when I did this I had a low tone the other direction, when I dug it I found I had a gold ring and a small piece of iron in the scoop at the same time on my 3rd or 4th scoop that I dug, it was about 7-9 inches deep.
I was also told by the experts to sweep till you leave the beach, one day I was sweeping all the way to the wooden steps where I was going to wash my excal off in the shower at the end of the day, as I was going home then, nothing nice found that day. I found a nice gold diamond ring less then 2 foot from the wooden steps leaving the beach....