There is no fixed number, but recency, quality, and response rate all factor into Google's local ranking algorithm. A business with 15 recent reviews will typically outperform one with 50 old reviews and no recent activity. Google values evidence that a business is actively serving customers.
For Geneva businesses competing in the Finger Lakes market, a baseline of 10 or more recent, substantive reviews with owner responses puts you in a competitive position. Community Proud includes a review generation and response strategy in all local SEO engagements, targeting consistent new reviews rather than a one-time push.