Unit 21 in Arizona is noted for its challenging terrain and varying elevation, which can impact accessibility and hunting strategy. Hunters frequently mention the importance of scouting, with several emphasizing the advantage of arriving early in the season to understand the movement patterns of game such as deer and elk. Many users highlight the benefit of having a reliable vehicle due to the rough road conditions, and some suggest focusing on water sources, as they are sparse and attract game. Overall, the sentiment is positive, with emphasis on preparation and adaptability as key to successful hunts in this diverse unit.