Megan McLean, a user research manager at Spotify Advertising, shares her insights on navigating research challenges for vast user bases. She introduces the 'Rivers and Roads' metaphor, where rivers embody change and data flow, while roads represent structured planning. Megan emphasizes the importance of prioritizing high-risk, low-clarity research questions to maximize impact. Her three-part prioritization framework focuses on assessing uncertainty, measuring potential impact, and prioritizing decisions that are hard to reverse, ultimately linking insights to strategic product development.