I know most people say you should be able to clip out with both feet, but I always clip in and out with the left. At this point, the motion is so natural, I don't think about it. I have never not been able to get out of my Speedplay pedals.
When I first got clipless (9 years ago), I used my right foot. Then I switched, for a reason I don't remember. I am a "left sided" person, except for my writing hand, in that I am just stronger on that side. I can't even approach or get on my bike from the right side, or walk it on the right side! The funny thing is, when I mountain bike, I can unclip/put my foot down on the right fairly smoothly, although I only do it to "practice."
I don't understand when I hear some say they clip out of both pedals every time they stop. There is no need to do that or put both feet down. While it might be good to be able to unclip with each foot, I don't think it's necessary to do it at the same time.