One of the key markers for school leadership (not just the Head, but anyone who is part of a leadership team) ought to be "learning agility," or the ability to learn quickly, apply those lessons, observe and measure the impact of those lessons, and rethink/adapt/adjust strategy, going forward.
What does learning agility require?
It requires emotional intelligence, maturity, and resilience.
How does one acquire those attributes?
They result from experiences that are emotionally-charged and very challenging, often requiring personal sacrifice. That kind of learning "sticks." Not only does it stick, it fundamentally changes people.