Context Maps are able to answer a high variety of questions such as:
how does the model of a given system propagate through an application landscape?
which kind of influence does a certain team have on others?
who has an influence on a given team?
how are politics being played?
As you can see: these questions are very specific, and we can answer them based on a big context map but such a context map will sooner or later turn into an information overload.
Therefore:
Work with smaller context maps, aimed to answer specific questions. Only include those patterns to these smaller context maps that help you in answering these questions.