Written words can be chosen with greater deliberation and thought, and a written argument can be extraordinarily sophisticated, intricate, and lengthy. These attributes of writing are possible because the pace of involvement is controlled by both the writer and the reader. The writer can write and rewrite at great length, a span of time which in some cases can be measured in years. Similarly, the reader can read quickly or slowly or even stop to think about what he or she has just read. The written word appeals more to a contemplative, deliberative style.
Speeches can also be precise and indeed they ought to be.
But precision in oral communication comes only with a great deal of preparation and compression. Once spoken, words cannot be retracted, although one can apologize for a mistake and improvise a clarification or qualification. One can read from a written text and achieve the same degree of verbal precision as written communication. On the other hand, oral communication can be significantly more effective in expressing meaning to an audience. A speaker has significantly more control over what the listener will hear than the writer has over what the reader will read.