Marsha the overprotective mother never lets her kid go out without boots on, even when the sun is shining. These aren't real people of course, they are stereotypes. We always know what to expect from them because they are always the same. But that's just the problem, audiences want surprises. They want to see unique, original people who do unexpected things.
Archetypes are a special case.
Gods, angels and devils are archetypes. The policeman on the corner, doctors, nurses, teachers, scientists, and other authority figures are often archetypes, especially if they make brief appearances. These are people from whom we know what to expect. There is very little characterization and history needed for these. But even archetypes can be made unique by giving them personality, attitudes, a mission.