Action plans offer the opportunity help people think through the various challenges they face and apply some type of plan on how to overcome these difficulties. Whether discussing students, employees our yourself it is beneficial to consider the benefits of implementing action plans in a way that encourages greater insight by the person writing them. Insight sometimes leads to higher levels of performance.
In my experience in labor relations and as a professor in business I find that performance issues may not be willful but are a result of a lack of experience or understanding. For example, in labor relations I have found attendance to be a major employer concern. Through the standard grievance process employees can promise to make it to work on time but without an action plan the problem isn't likely to be resolved soon.
The same idea applies to students who consistently fail to turn their work by class deadlines. Each assignment they scramble for some excuse that will get them off the hook. The problem is not the creativity of the excuses but their processes. Understanding how chronic poor performance is part of a process of thinking is beneficial for finding solutions.
Before giving grace to poor performance consider requiring an action plan to ensure the person has some understanding on how to improve the situation. Requiring the person to develop a plan on how to change their processes helps them think through what is causing the problem and how it can be improved. They can search through their strengths and weaknesses that help them discover equitable solutions to the problem.
Most of us live our lives by patterns and reflecting on those changes needed to adjust the pattern is beneficial to sustainable performance. An employee who has an attendance problem could discover the necessity of starting early, putting out their items the night before, and getting plenty of rest. A student who turns their work in chronically late may need to start assignments at the beginning of each week and also devote a full hour to writing each day.