One advantage of the one-shoe-off-and-one-shoe-on technique could be that you get to practice spinning full circles with one foot and old-fashioned mashing with the other. Even with cleats and clipless pedals on both sides, I sometimes have to ride for a few yards with one or both feet unclipped, for instance because there's a bit of traffic and I'm maneuvering a curve -- not a good time to "grope" around to get the pedal turned up the right way and the cleat centered over the clip spot.