Usually more than once. Possibly even the same fonts. Yes, more color and a big, flashy index. Yes, more likely a standalone section led by editorial or advertorial content. Yet once you get to the ads, they look the same, except squeezed into narrower columns and smaller type.
Classifieds have tremendous utility for people.
They are worthy of design attention. Va. From a design perspective, you can bet that your classified section could be better. It could save space. It could be legible. It could be better organized.