What is the rule-of-five when it comes to car parking in residential areas?

The rule-of-five might reflect an assumption that an unrelated group will be noisier, generative of more traffic and parking problems, or less stable than a related group of the same size. "But none of these observations reflects a universal truth. Family groups are mobile today, and not all family units are internally stable and well-disciplined. Family groups with two or more cars are not unfamiliar." (City of Des Plaines v. Trottner (1966) 34 Ill.2d 432, 216 N.E.2d 116, 119; see also State v. Baker (1979) 81 N.J. 99, 405 A.2d 368, 372.)