Here's a fairly long answer to a short question. If you raise your disc too high you will eliminate some gold, if you become too selective on the high end to eliminate pull tabs, you may loose silver. I can tell you even the most expensive detectors, despite the displays and cost, don't have the ability to eliminate trash perfectly. As you probably know, many trashy targets have rough edges or get choppy as you rotate the disc knob, and that gives you a bit of an edge. Here is a good real life example of why you need to dig it all. In one of my parks, there are hundreds of these 1.5" round, seals that you find on small plastics juice bottles. These sound solid, have sharp edges, small foot print. They disc out just before the nickle mark and initially I though to just ignore these hits. After about a week or so I had one of these hits but thought, what if? So I dug it and found a 14K gold ring. There is the plus side to digging trash. I keep my trash in a clear, zip style bag. I went to a new park and was approached by one of the park maintenance guys. When he asked how I was doing I pulled out my trash bag and said great, and I'm helping you guys clean out the trash. I also showed him a piece of can-slaw and mentioned how dangerous it was to the folks enjoying the park. He quickly agreed, thanked me for helping keep the park clean and safe, wished my luck and left. Now when they see me they always say hi and ask how I'm doing. By the way I keep my trash bag visible. My ring and jewelry finds increased tenfold the last two years for mainly two reasons. 1) I overlap my coil swings at least 50% and I dig every target. If your coils not over it, or your not digging it, you stand to loose a once in a lifetime find. This is a great hobby and offers some excellent rewards, and you have an excellent detector to make it happen.