There was a really interesting anomaly last year where, due to a political dispute, Serbia and Kosovo refused to synchronize their grids, causing the entire Eur

There was a really interesting anomaly last year where, due to a political dispute, Serbia and Kosovo refused to synchronize their grids, causing the entire European grid to drop from 50 Hz to 49.996 Hz, in turn causing grid-based clocks to run 6 minutes slow by the time the issue was resolved. [1] I don't disagree with you that grid frequencies are generally very accurate and they are a practical clock source for cheap clocks, I just found that interesting. [1] https://www.reuters.com/article/serbia-kosovo-energy/serbia-kosovo-power-grid-row-delays-european-clocks-idUSL5N1QP2FF https://www.reuters.com/article/serbia-kosovo-energy/serbia-...