Last Monday, I set my watch ahead by a minute, because it was running a bit slow. On Thursday, I noticed that my watch was fast by an hour. Apparently, I actually set it ahead by one minute plus one hour, and then only checked the minute hand for most of the week.
Which leads me to wonder: would a watch with only a minute hand be more or less useful than the normal kind? Unless you've just woken up from a nap, it's usually easy to guess which hour it is, and in bad light it sometimes takes a second to tell which hand is which. Plus, you wouldn't have to worry about adjusting your watch to the local time when you travel.
It's an opportunity for someone. If only I had the entrepreneurial spirit.