in 3, roads everywhere is pretty much standard procedure. makes everything look ugly, but tactically sound.
in 5, roads have recurring costs so you only want them to go specifically where they need to.
as someone who has played both 3 and 5, i like 5 better for making combat much more interesting and even some of the graphical beauty. diplomacy still sucks balls, but still good games.
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There is no shame in not knowing; the shame lies in not finding out