I knew about this trick for a longer time already, but also thought it would be slower. The recent discussion at TASvideos made me start to doubt, so I went ahead and tested it more carefully to be sure. Now we have the answer.
Though I seriously doubt that it will actually save ~30 seconds. First you loose time on X-ray. (and you loose health which will slow down WS considerably) And you need to magically gather up another 10-15 PB's and 5-10 or so supers from thin air to make the ammo go around. I don't really now where this can be done. It will likely save time in the end but the sacrifices will be very big no doubt.