That is the only true requirement to finding things with a metal detector. Of course, this does not apply if you are searching for meteorites or gold. All else requires the past or present existence of people. First, I'll give a list of places that anyone can hunt. Then, I'll show you some of the places I personally hunt.
Many people have their favorite places to hunt.
This will vary from person to person. If asked to name a favorite, I couldn't. I like parks, yards, beaches, and just about any other place I can hunt. I could go on and on here. Research will give you ideas to what sites are old and to where sites once existed that no longer exist.