Because of the many ways by which messages may be lost or garbled, a message should be communicated in as many ways as possible. This corollary means that if you give communication a chance to fail, it will fail. If you, as a communicator, are careless, indifferent, unskillful, or just plain lazy, you will usually fail in communication. Even following careful preparation, a flurry of unrelated realities may create static which interferes with the easy flow of data. Key people sometimes die in mid-sentence.
Sound systems collapse.
Printing deadlines are missed. Unexpected storms arrive. Checks are delayed in the mail. Receivers may think they understand your message. In reality, they often misunderstand it or just want to humor you or do not want to admit misunderstanding.