I'm not so sure about that. The implication of the blurred frame is that some part of the body started at the left, but it's current position is at the rightmost part of the blur. Without the blur, then yes, the middle part of the motion would be quicker, but with the blur, the speed of the motion is implied. Reducing the time on that frame will apparently help, but I think that's because the frame is wrong, rather than that it should be quicker.

Note the blur starts behind where the elbow started. What is it that got blurred? Note also that the implication of the blur is that the fist is already fully extended to the rightmost point of the blur, which makes the stance fairly strange.
The example Seiseki provided also illustrates the other problem I mentioned before. You're starting out with the punching hand at the front. This means that your get ready involves turning away from the viewer, which adds a delay to the animation. In a game, this could make the punch feel very unresponsive.
Notice the difference, here, though:

The punching hand is already further back, so there is no need for the character to turn away from the viewer to prepare for the punch. Instead, he finishes the punch turned away from the viewer, and returns to forward
after completing the punch. In other words, you'd be better off punching with the other hand.