A global logistics company is experiencing significant performance degradation during territory realignment. Their Enterprise Territory Management 2.0 model includes a 7-level territory hierarchy and over 500 assignment rules that run on Account updates. During peak hours, updates to Account records frequently time out. The org contains 15 million Account records. An architect has been tasked with optimizing the sharing model to improve performance without compromising the complex access requirements. Which approach should the architect prioritize?