Many people at our Japanese restaurant in Seattle like to start their sushi meal by pouring out a small pool of soy sauce for easy dipping. This is an acceptable practice here in the United States, but you would do well to leave it behind if you ever made your way across the ocean to a sushi restaurant in Japan. It is here that wasting soy sauce is considered very bad form.
Soy sauce is an important condiment to the Japanese, so ending a meal with leftover soy sauce is frowned upon. Try to only pour out a small amount so that you never take much more than you use. Further, most of your sushi shouldn’t require much in the way of condiments in the first place.