NavList:

Regarding whether watches should be worn or kept fixed vertically, I believe it depends on whether it's a mechanical or quartz watch.  For a mechanical watch, keeping it on your wrist would expose the oscillating balance wheel to all sorts of random torques that can cause it to briefly move fast or slow, while keeping the watch stationary means the only external source of torque is gravity.  In contrast, the vibrations in a quartz crystal movement aren't really "directional" and are more shock resistant; most quartz watch manuals I've read usually say "playing tennis is OK, operating a chainsaw isn't (unless it's a G-Shock model)."