What is a consequence of excessively running the APU during ground operations?

The consequence of excessively running the APU during ground operations primarily involves increased maintenance demands and higher operating costs. Continuous operation of the Auxiliary Power Unit can lead to wear and tear on its components, resulting in more frequent repairs and potential replacements. This not only elevates maintenance schedules but also increases the overall cost of operation due to necessary servicing and parts needed to maintain the APU in good working order. The APU, while essential for providing power and air for air conditioning and engine start, does not provide benefits to performance when overused; rather, its excessive use can create operational inefficiencies and inflate operational budgets.