Added sensitivity will make a metal detector more susceptible to interference, as well as sounding off on any small piece of metal in the ground. Like in horse power; if you have a 500 HP car, you probably don't need to use all of that HP to get to the store, but it's nice to have.
A lot of people who are having interference seem to be right out of the box (testing in the house) or near something electrical. When you get chatter, knowing what is causing it and what controls help to reduce it are key. Switching frequencies, backing off the sensitivity, adding more discrimination, etc will solve the majority of it. It takes practice to master any metal detector, and the more sensitive ones can take a while longer.