Yeah, I think the roads in Rohan make perfect sense given their culture.
@Jetfire301 You make a good point, and I agree that many roads would make sense they way they are. However, I guess my thought was that some of the "best" (i.e. most important) roads in Gondor wouldn't be limited to cobblestone, and instead might be viewed as made of flagstone/brick, which would be presumably more durable. In addition, if you've ever seen a real cobblestone road, they're not just a bunch of random stones buried in the dirt, but instead stones held together by mortar or cement. Provided they're well-maintained, you wouldn't see much of any grass or weeds growing between them. Like I said though, this is just one dude's opinion, and I know it's all a matter of interpretation.