Me being accident prone means that if I practice with just one foot, all of the emergency situations I'll get into will require unclipping with the other foot. It just works that way, so I practice with both.

Usually I only unclip with one, and it's usually the right (often so I can lean on a curb at a stoplight), so I don't have to make a decision about which to unclip too often. That would take me all day!