Initially, the author could easily manage a team of ten, understanding individual tasks and capacity. However, as the team grew to fifty and then ninety people, these old management habits became detrimental. The first lesson learned was that a leader cannot hold all context in their head as the team expands. Instead, multiple channels for information are needed, like check-ins and clear escalation paths. The second key insight is that a leader's voice must be amplified through others, emphasizing the importance of training and aligning managers. The third lesson highlights that heroics do not scale; relying on individuals to constantly save the day reveals underlying systemic issues. The fourth and final lesson explains that shared decisions do not necessarily mean fast decisions, distinguishing between collaboration and paralyzing consensus. By confusing these, decision-making can be slowed down significantly. The author learned that excessive collaboration can hinder speed, advocating for the "disagree and commit" principle. Ultimately, leaders often burn out by applying startup-stage tools to larger companies. Effective management at scale requires the leader to step back and let the system support the team.