I have to admit, it's a practice that makes no sense to me. If you're the one who sets the clock, you know perfectly well it's set ahead. So how do you avoid just automatically subtracting those minutes when you look at the clock? I suppose it might work if the purpose is to trick someone else into thinking it's later than it is, but not more than once. But I've never heard anyone say that's why they have their clocks set forward; it's always an attempt to correct their own lateness problem.
But I have a solution! A self-adjusting clock that will set itself up to 10 minutes ahead or behind. The way I see it, for some people, being on time for something isn't rewarding enough, nor arriving a few minutes late shameful enough, to promote the good behavior of punctuality. But being 20 minutes late? That risk may be enough to promote the desired behavior. I should pitch this to someone who does behavioral research UW-Madison.
Speaking of clocks, this one's kind of cool:
Via Awesome Inventions on Facebook. Designed by Nazar Şigaher.
Except how do I know it's 6:50 and not 10:35? The hour "hand" looks like it might be slightly wider than the minute hand, but that's a pretty subtle distinction to expect people to make at a glance. Still, an interesting idea.