The only reason anyone noticed the error with the 11th of the month was because we had enough similar phrases (8th, 12th, etc.) that we could make a statistica

The only reason anyone noticed the error with the 11th of the month was because we had enough similar phrases (8th, 12th, etc.) that we could make a statistical argument that something was amiss. It would be hard to even detect most other errors in the database.