Even a watch that has stopped tells the correct time twice a day.
Maybe, but one that loses a minute a day is only correct every 720 days - if my logic is right

I can think of one good alternative use for an expensive watch - its a useful way of passing on money to the kids outside IHT.
If the stopped watch shows say 11.00 it is guaranteed to be correct twice a day, few watches can match the atomic clock used to measure time accurately .Some 400 atomic clocks around the world contribute to the calculation of International Atomic Time (TAI), one of the time standards used to determine Coordinated Universal Time (UTC) and local times around the world. Satellite navigation systems like GPS, GLONASS, and Galileo also rely on precise time measurements to calculate positions accurately.
Currently watches are outside of CGT......not so sure about Inheritance tax if mentioned in the will.