Topic summary
Quartz watch

Extracted from the Wikipedia article Quartz clock.
Temperature and frequency variation
Quartz watch manufacturers use a simplified version of the oven-controlled crystal oscillator method by recommending that their watches be worn regularly to ensure the best time-keeping performance. Regular wearing of a quartz watch significantly reduces the magnitude of environmental temperature swings, since a correctly designed watch case forms an expedient crystal oven that uses the stable temperature of the human body to keep the crystal oscillator in its most accurate temperature range.