Your experience as a multi-unit manager is a valuable factor, and your reasoning about the specifics of aggregate planning is objective. One of the important criteria mentioned is forecasting to ensure flexibility in work. You have noticed that buying and selling schedules are dynamic, and customer satisfaction depends much on how effective aggregate planning is. As Demirel et al. (2018) note, traditional forecasting approaches do not allow building flexible working models, and your example proves that many aspects need to be considered to achieve high sales performance. Nevertheless, I would advise you to pay attention not only to forecasting but also to additional factors affecting the stability of sales. For instance, more attention could be paid to how to influence the level of production to avoid a surplus of goods. At the same time, you mention the roles of personnel, advertising directives, and other criteria, which is a valuable reference when discussing the topic of aggregate planning.
Your discussion includes relevant factors related to aggregate planning. In addition, you mention the most important aspects of this approach, such as forecasting and the optimization of operations. However, I would recommend paying more attention to your personal experience to describe not only the theoretical foundations of aggregate planning but also valuable practical factors. Moreover, you mention personnel problems in your previous workplace, when employees were forced to quit. According to Noegraheni and Nuradli (2016), aggregate planning is a model aimed not only at forecasting but also at staffing needs, and you could assess how this approach might have affected the staffing policy in the team. Nonetheless, your reasoning is logical and relevant, and the fact that you mention delays in order fulfillment is a valuable addition to the problems associated with the lack of adequate aggregate planning.
References
Demirel, E., Özelkan, E. C., & Lim, C. (2018). Aggregate planning with flexibility requirements profile. International Journal of Production Economics, 202, 45-58. Web.
Noegraheni, E., & Nuradli, H. (2016). Aggregate planning to minimize cost of production in manufacturing company. Binus Business Review, 7(1), 39-45. Web.