A good template will provided a step_by_step approach with explanations as to why each step is proposed. The strength of the marketing plan derives from the integration of each step. So if you leave out a step, you may undermine your own plan.
The template usually provides ways to do keyword research, methods to build websites or blogs and strategies for getting your site listed in Google. Improvement to traffic and profits can be seen when you make use of this kind of template.