Final answer:
The statement that cause-and-effect speeches are usually longer than problem-cause-solution speeches is false; the main difference lies in the organizational structure, not the length.
Step-by-step explanation:
The main difference between the cause-and-effect pattern and the problem-cause-solution pattern is not the length of speeches, but rather their organizational approach to presenting information. Therefore, the statement that cause-and-effect speeches are usually longer than problem-cause-solution speeches is False. In the cause-and-effect pattern, you might begin with an explanation of the cause(s) followed by an explanation of the effect(s), or vice versa. In contrast, the problem-cause-solution pattern involves identifying a problem, explaining the causes of this problem, and then presenting a solution.