I am unaware of whether a “chronometer rated” tuning fork movement has to meet higher standards than a tuning fork movement that is not chronometer rated, be it a UG, Tissot, Omega, Accutron, or any other tuning fork watch, be it the ETA movement, or the Accutron. But in good condition, properly adjusted, these tuning fork movements are usually quite capable of being accurate to within one minute per month.
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