Hunters discussing California's Zone D-4 highlight its challenging terrain and the importance of scouting before the season due to its diverse landscape and varying elevations. They emphasize the need for patience and strategic planning, as deer movement can be unpredictable, often influenced by weather patterns and pressure from other hunters. Many recommend focusing on less crowded areas within the unit to increase chances of success and suggest paying close attention to water sources and feeding areas. Overall, the sentiment is that preparation and adaptability are key to a successful hunt in Zone D-4.