a dead clock is correct twice a day
Even people who are usually wrong can be right sometimes, even if just by accident. From the idea that the stationary hands of a broken clock will still display the correct time at two points during the 24-hour cycle. I know you're sick of Gran's lectures and think she's out of touch, but you can learn a lot from her. Just keep in mind that even a dead clock is correct twice a day! A: "You know how I feel about the mayor, but even I think he's right this time." B: "Even a dead clock is correct twice a day."