Continuing on the idea that non-local, general insulation advice should be questioned, and your insulation should be determined by your own micro-climate, I came across an easy to use tool that can assist you in making a more intelligent decision:
...as you see, the climate characteristics for your state vary considerably.
Also, this wonderful map is "clickable", so you will be able to find precise data for your own home. When you click on the map you will find a large amount of very useful information. Which will show you, for example, that the state recommends ceiling insulation R-values that vary from R-30 to R-38, depending on your precise locale, and not a general R-30 for your state, a state that is so rich in topographic and climatic diversity.
And here is another lovely gem of a document:
...this little ruby has obviously been written by forward looking North Carolinians, who want to go beyond code and see substantial energy reductions in your fair state.
A quick scan revealed that they are pushing for ceiling insulation levels of R-42 minimum... interesting!
This paper also goes into fairly rich detail on other energy reduction benchmarks that could be wise to meet or exceed.
I don't think a man can have too fast a horse, too much money, or too much insulation.
Best,
-AC