Heres my example from another comment:

Ie, splitting a city(with a rural area in a crescent shape around it) into two equal districts down the middle each with a sizable urban and rural population(say this gave 45% rural, 55% urban in each of these districts which is pretty reasonable), vs giving the city its own district and the rural area its own district. The first option may be more “compact” but in my opinion would lead to unfair under representation of the rural voters- same as if the demographics were swapped. Districts are supposed to “represent a community” not just be compact.