Question: Why some people are wearing their watches on the left hand while others prefer the right hand?

In 1524 Peter Henlein created the first pocket watch which was too heavy to wear them on a hand anyway so the discussion became actually for the first time in 1868 when Patek Philippe created the first wristwatch.

Now most people wear their watch on the left hand, some argue that right handers prefer the left hand to avoid getting the watch damaged and there are more right handers than left handers. Nevertheless a lot of right handers wear their watch on the right hand and vice versa. So this can not be the sole answer.

Others argue that wearing a watch on the left hand is a tradition and a very small group claims that a battery-powered watch should be carried on the right side for medical purposes to protect the heart.