Sometimes the only way to really clean a good site out is by using no discrimination and digging every signal response, even a break, slight raising or lowering of your metal detector threshold.
If I am taking no prisoners at the beach or in land, I go all out by taking a spade or rake with me to a site I feel is going to produce something good.
At my favorite sites, I will often dig down a couple of feet and even rake the spoil piles detecting every metal target possible.
Like I often say in my blogs and beach hunting related books, I go to the beach to find good stuff not to walk along the beach for hours on end hoping to stumble across something good.
Discrimination and notching out select targets is good at the appropriate sites, but at many of my favorite sites I need to know Im getting it all which means digging all I can in my allotted search time.
As a tourist beach hunter I know the effects of both iron and target masking, I use a little discrimination knowing I am potentially trading some high value targets to detect more lost tourist gold faster.
As a Spanish treasure hunter searching for old coins and artifacts, I know Im in for a work out.
There are times to dig it all and roll the detecting dice, it just depends what you are searching for and where.
My advice to beginners is always to dig it all as you learn to interpret signals and get to know your metal detector.
Bells and whistles on metal detectors help in certain situations, but until you have experience you are going to have to dig it all or miss out on one of metal detecting greatest pleasures the surprise find.
I will leave you with two things to mull over, if your metal detector cannot identify a target at depth it will reject the target no matter what it is and larger targets always over power smaller targets.
Put a gold coin close to crusty bottle cap, sweep your search coil over them and you will see why you have to dig it all to be sure.