Jason Fried:

So what’s the net effect of this tiny little design detail that the owner may not even understand? Well, it looks like the watch is already half-way out of power after the first day, so it encourages the owner to wind the watch more frequently. To keep it closer to topped off, even when it’s not necessary. This helps prevent the watch from running out of power, losing time, and, ultimately, stopping. A stopped watch may be right twice a day, but it’s rarely at the times you want.

Small detail, material behavior change. Well considered, well executed, well done.