I've been wondering about the same thing. That's why I want to try this new wick in my mods. For quite some time now, I have been tying the three strands together, which seems to work better. Look at the ones in the following photo. You will see a black thread near the ends.
Also, notice that the strands are clinging to the wall of the tube. When the liquid level is low enough, additional juice can be seen between the strands and the tube walls. I believe this adds to the capillary action, especially if the strands go straight down the walls from the slot in the cup to the bottom of the tank.
In the case of this particular mod, the action is too much. It wicks very well when vaping back to back, but if the device is left standing upright for an extended time, the tank will empty out through the air intake and flood my desktop. A few people have said that this is impossible, but I've had it happen so many times that there is no doubt about the fact.