I think there is a lot of guidance for classifying documents. I don't think it's always applied evenly across departments and agencies, and it might not always be well known among the people who need to be engaged in the classifying of the documents in the first place.
I think it really depends on who's classifying and what their level of comfort is in terms of classification. There's a system there for determining what level of classification a document should be. My impression is that it's probably not applied evenly.