Today I was shooting two persons with my camera (Canon 7D) on a tripod. One person, the one I wanted to be in focus, was composed so far out of the center that I don't have any focus point close to their eye.
I tried to use the closest focus point to their eye, and as a result I ended up with the eyes being out of focus.
Since the camera was mounted on a tripod I could not apply 'focus and recompose'. Generally, I could use live view, but moving the focus square is a very slow process and the mode eats the battery for breakfast.