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.
Unfortunately, people who are new to Internet marketing often fail to follow the guidelines provided in a marketing plan template because they are tempted by some other new strategy. They end up mixing up strategies and leaving out key success factors.