The fourteen-day rule

A movement that has just been rebuilt behaves like a new employee: talented, but unpredictable. Six positions on the timegrapher tell us how it performs in theory; only fourteen days of continuous running tell us how it performs in life.

Day by day, the rate settles. If any measurement drifts beyond its promised corridor, the watch goes back to the bench — and the counter starts again. Fourteen quiet days are the cheapest insurance precision can buy.