All AVMs rely on the coverage, accuracy, and recency of the data they use. Valuation accuracy varies depending on a wide range of factors. The most significant factor is the homogeneity of the target property to surrounding area properties and the number of recent home sales in the area.
Generally, all AVMs tend to be less accurate in rural areas and in areas of low market liquidity. AVMs are also less accurate when valuing properties that are unusual, much larger than average, or have uncommon features.