You can also do that if you are rushing to get a plan created. This will make your job a lot lighter because with a template, you would just be filling out a form. No need to think that hard and you can also make sure that its content is complete. Since the person who made the plan previously have revised it several times, it is sure to be accurate.
Some of the better marketing plan templates provide detailed instructions for newbies and do not presume that they know how to take each of the steps required in the template.