I have duck walked it once... It was my turn at the 4-way stop. Left foot on pedal at 10 o'clock and right foot on the ground. Transferred weight to the left foot to start moving and push myself into the saddle. Before the pedal made it to 6 o'clock... BAM! huge calf cramp that hurt so bad I nearly fell over. Got off immediately and waddled my way to the sidewalk.
If I'm on the sidewalk and getting ready to enter a busy street at an intersection, I'll walk my bike to the far side of the intersection in the direction I'm headed. That way, I get a better view of traffic coming down the street and at the same time avoiding cross traffic. If it's a calmer street, then I'll just enter the street mid-block.