Yes, but definitely not the norm. As a consultant, I once inherited a system (that I successfully passed off to the new permanent CIO) that was immaculately documented and the documentation was updated every single time a change was made in the environment. Needless to say, the service level this company's employees experienced was very low because the IS staff did nothing but document miniscule changes to the systems.
Normally, there exists no documentation that is up to date. That is why I am so practiced at systems assimilation.[:P]