I tend to approach content strategy by observing how a single type of content fits into the larger picture. But it is broader than that. However, content strategy is still a fairly new discipline.
Rachel Lovinger, in her landmark content strategy article from 2007, talks primarily about content strategy as a single piece of content as it appears to the user. She touches on content types in their broader context but spends more time on the design of a single piece of content.
Good reading from someone who helped to put a name to the work that many of us have been doing for a few years now.