|This page in a nutshell: Writing an encyclopedic entry about a subject will involve generalizations. Avoid the temptation to engage in original research by finding every example of a phenomenon, or every exception to a phenomenon.|
Encyclopedia articles are a summary of accepted knowledge on a given subject. Making an appropriate summary involves describing theories and observations that come from mainstream scholarship and news. Naturally, every theory can be demonstrated using examples or counter-examples. However, this tends to make articles less readable and reliable because, mentioning too many examples, or discussing an example with irrelevant detail, takes the article farther away from its original point.
Writing about examples of the phenomenon
One, or at most a few examples about the subject matter under discussion, should suffice. Examples help readers expand their understanding of a concept, and typifying it. Before adding yet another example, pause to ask whether it will help readers unravel the many facets of the concept, or drag them into needless detail specific only to that example, thus deviating from the central theme of the concept.
If the number of examples in an article become too many, consider pruning them, or creating a separate list at the bottom of the article. Where the list of examples as a whole has verifiable cultural significance, consider creating a separate article.
Writing about exceptions to the phenomenon
Any theory or phenomenon lacking a reliable source directly supporting it may be removed. But avoid removing theories attributed to a reliable sources without discussing it first.
A theory that appears in many reliable sources should never be removed, even if that theory is not 100% true. The standard for inclusion in Wikipedia is verifiability, not truth. Rather than engaging in original research by trying to invalidate a theory you disagree with, look for criticism of that theory from reliable sources on the subject. It is always preferable to describe an alternative explanation from a reliable source, rather than synthesizing a thousand counter-examples.
Balancing coverage of a phenomenon with intelligent criticism is a part of creating a neutral encyclopedia. However, counter-examples and criticisms that come from sources that are unreliable or thoroughly discredited should be removed. Wikipedia is not a compilation of every fringe theory or opinion piece about a subject. Treat each perspective on a topic with proportional weight.