Hunters discussing California's Zone D-15 emphasize the challenge posed by its rugged terrain and dense vegetation, which requires good physical preparation and strategic scouting. Many mention the area's popularity, leading to crowded hunting conditions, especially during peak season. The need for early scouting trips is a common theme, as understanding the habits and patterns of deer in this diverse environment is crucial for success. Hunters recommend leveraging elevation changes and seeking out less traveled spots to increase the chances of encountering game.