My dad wore his watch on his right arm, he was right handed. He was in the navy handling the canon. Every day he had to test the canon and feel with his left hand if everything was alright. The gap was so narrow that he could not wear his watch on the left arm. So he switched. After the navy he still wore his watch on the right arm. He met other people from the navy wearing their watches on their right arms. Everyone had the same reason and never moved it back to the left arm.
Duran Duran