NAP consistency: citation building impact

We all know NAP consistency is absolutely critical for local SEO, directly impacting local search ranking. However, even with diligent data aggregator submissions and manual cleanup, we're still seeing subtle, persistent inconsistencies in our local citations across various directory tiers, especially after recent data migrations. What advanced strategies or tools are others using for truly granular data reconciliation and validation, beyond the usual suspects, to mitigate these nuanced discrepancies and their impact on local search visibility? Anyone faced this before?