Why does Hilary Erickson emphasize the importance of flexibility during labor?

Hilary Erickson emphasizes the importance of flexibility during labor because having rigid expectations can lead to disappointment and stress. She believes that while it's important to plan and prepare for your birth, it's equally crucial to remain open to the reality that the situation may not unfold exactly as you've envisioned. She encourages expecting mothers to think positively about their birth, but also to be ready to adapt and go with the flow. This approach can make the labor process easier and less stressful.