So, each 4 seconds error in the time will result in a position error of 1 nautical mile. Longitude is the coordinate affected by time errors. In fact, if you don't have the correct time, you can't calculate your longitude by celestial navigation. The traditional way to calculate the time using celestial navigation is by performing a Lunar Calculation . This uses the Moon fast celestial sphere movement as a clock.
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In the old days of mechanical watches, keeping the time was a real nightmare. Chronometer paces were affected by boat movement and temperature. They usually carried many chronometers, to improve reliability. They were wound once a day, always in the same time by the same person and with the same number of turns. All these measures were to make sure that these devices behaved in a predictable way.