There are 2 kinds of documentation we often generate inside of an upfront strategy/IA process.
Live documentation is any artifact we use to express design decisions we make along the way. It’s a malleable and active representation of what we’re creating. Live documentation evolves, grows, changes. It’s an extension of our short term working memory.
Dead documentation is any artifact we use to express the fact that we’ve spent a lot of time working on something. It’s a hard to change, static representation of stuff that has little to do with what we’re actually creating. Dead documentation sits in the project folder or on the shelf.
The trick is to do more of the former and less of the latter.