I never would have noticed it until trying to get the slow speed escapement cleaned and back into the camera...
The total time that the focal plane shutter on a Barnack Leica is fairly long. Taking pictures of a fast moving object can produce distortions. This will not happen with a Leaf style shutter. I adapted a Kodak 50mm Anastigmat Special with shutter to S-Mount for my Nikon once upon a time.
Mounting a leaf shutter in front of the lens of a Leica (or in the following respects similar camera) can yield
-) undistorted images of moving objects*
-) taking double exposures in fast succession if that leaf shutter is of the self-cocking type
* as the leaf shutter must be fairly large to not vignette at the front lens, it likely is of the rather slow type with higher risk of unsharpness of the moving object