In speaking we are not always concerned with precision in expression. We can make a statement, repeat it, expand it, and refine it according to the reactions and interjections of our listeners. Speech can be telegraphic. Speech has a higher tolerance for repetition of a phrase or sentence than writing. Written statements must be constructed more carefully, concisely, and coherently to ensure that our meaning is clear.
Repetition leads to redundance and the loss of the audience.
Cognitive Factors Speech develops naturally and early in our first language. Competence in writing usually develops much more slowly in first language acquisition. Writing is usually learned through formal instruction rather than through natural acquisition processes. Writing requires extensive previous learning. Production is rarely rapid or fluent nor is meaning always clear.