In the context of the excerpts provided from the work of executive coach Ed Batista, the hardest question he encounters is not explicitly stated. However, it can be inferred that one of the most challenging issues he discusses with his coaching clients, who are often technology company CEOs and MBA students at Stanford, is finding the balance between accountability and empathy within leadership roles. Batista emphasizes that viewing accountability and empathy as mutually exclusive is a false dichotomy and a misunderstanding that empathy equates to agreement. He suggests that the integration of both accountability and empathy is essential to defining an organization's culture and ultimately influences the leader's behavior.

Additionally, Batista explores the complex nature of work and productivity, challenging the binary choice between working hard and working smart. He encourages leaders to consider the nature of the systems they operate within and to recognize the relationship between effort and results, which varies depending on the timeframe and whether the system is characterized by increasing or diminishing returns.

Furthermore, Batista delves into the struggle leaders face in managing their time effectively, balancing work with rest, and setting boundaries to ensure a sustainable lifestyle. This includes addressing the tendency of leaders to be consumed by the "puzzles" of their work, which can lead to compulsive working habits and a lack of attention to personal well-being.

In summary, while Batista does not single out one "hardest question," the recurring themes in his work suggest that the complex challenges of integrating accountability with empathy, understanding the nature of work systems, and managing one's time and energy effectively are among the most significant and difficult issues that he helps leaders navigate.