I keep my screen as open as possible. I have iron mask set low, just enough to reject a small piece of iron like a bobby pin and I have my smartfind screen set to just take out the nails, so thats the upper left section, just a small portion.
Ive tried different patterns when I get deep signals or mixed in trash signals and patterns have almost always deteriorated the signal response. Really, just like other detectors, targets close to a rejected target are harder to get a clean signal on.
You have to listen more, learn the sounds more and pay more attention to the screen with open screens but I think its worth it.