There are many reasons for writing a work plan. First determine the purpose of writing, and then you can plan to prepare, so as to achieve twice the result with half the effort. Remember, most work plans have a time period (ie 6 months or 1 year).
In a company, a work plan can make your boss more aware of what you will do in the next few months, especially after the annual performance review, or before the team undertakes a large project. The work plan can also be used as a result document to be included in the resolutions of your company’s strategic planning meeting in the new financial year.

Academically, the work plan can help students establish a schedule for a large project. It can also help teachers prepare course materials for this semester.

As far as personal matters are concerned, the work plan can help you know more about what you plan to do, how you do it, and the day before it will be completed. Personal work plans, even if they are not strictly required, will help individuals keep track of their goals and work progress.