the above diagram is from the Vaquero which is a bit different from the Silver. When using the disc on the VAC you don't lose much depth but you DO lose quite a bit of depth with the Silver....the more you DISC, the more depth you lose. If you do an air test and all things are equal (all the different metals you're testing are at the same depth like 1 or 2 inches) then you can turn your disc knob to see where it falls out. But, while you're doing the air test, your Silver may be able to pick up a target at 6" but when you turn the disc you won't be sure if 1. your disc knob DISC'D it out or 2. if it's too deep for your detector to pick up now that you've lost some depth by turning you disc knob too far to the right.
The Silver really shines when you don't use any disc or just disc out iron. Digging sucks so dig faster! Go to youtube and look up COIN POPPING. If the target is close to the top (1 or 2") your Garrett Propointer can pinpoint it and....it'll be close enough for your detector to determine what it is by turning your disc knob to the right. Unfortunately, you may also disc out something valuable! For me, I'm way too greedy...I DIG IT ALL.