Simply a matter of chioce. As a person who hunts for old coins at old sites, many of the places I hunt are farm fields where houses were 100 years ago. By running in all metal, multiple tones, I can hunt by ear. That means I've "trained my brain"" to ignore the audio tones of the items I don't care to dig. (the low tones of ferrous targets and the mixed harmonic tones generated by man-made metallic trash). And concentrate on digging those targets with tones I like! Higher tones, and those that are consistent. Patterns are simply a place to store the accept/reject programs that work for you. And what works for me is accepting all targets and letting my ears act as the discriminator. Doing so reduces target masking. And, when hunting a 40 acre field in search of where the building site was, all metal / multiple tone allows me to "hear" (nails, trash etc) when I am getting close to where the old buildings once stood. I don't stop to dig most of the low tones. But at least I know when I'm getting close to where I want to be. JMHO HH Randy