How does aircraft design affect carburetor ice?
I've downvoted the answer from Habu because it ignores a major difference in engine design.  

For small GA planes, the Lycoming engines have the carburetor bolted to the bottom of the crankcase where it gets some heat from the hot oil.  Fuel/air exits the top of the carb where it is routed through pipes inside the crankcase where the hot oil further increases its temperature. This makes the Lyc generally resistant to induction icing.   

In Continentals, the updraft carburetor is not mounted on the hot crankcase but on part of the manifold assembly, insulating the carb itself from the heat of the crankcase, and the fuel/air mixture is routed directly to the intake manifold and not through the engine crankcase which holds the hot oil.  The result is that the TCM O-300 engine has earned the reputation of being an icemaker. The difference in the POH instructions as to how to fly each engine is directly attributable to engine design and it has absolutely nothing to do with the weather in Vero Beach versus Wichita.     

I'm going to post line drawing images of the two engines to illustrate the point. First: Lycoming.  Second: Continental 

What the original poster is missing is that for most of its history, the Cessna design used Continental engines.  Now that it has switched to Lycoming engines, the difference in the engines is probably zero, but they have not abandoned the former POH instructions as that might be confusing to the pilots that fly these planes.  After all, using carb heat more often as a default procedure for the Lyc powered Cessnas is a safe procedure.