If you wad it, you run the risk of getting a little bit on your fingers. Folding it gives you the confidence and peace of mind ("It's secure in there... cool..."). I'm saying, is all... is all...
The fold only a small flat area and is effective only on specifically directed zones. The wad is capable of not only doing the front work, but the wad also uses it's bunching abilities to scrape and cleanse the sides, providing more bang for the buck. You can then double up on styles by folding your wad (provided it was large enough to begin with) and then have a smaller, more compact wad for any stragglers.
fold...it provides strength, but also is reliable. with the wad, you could come up empty, and you risk skin on skin contact. the fold provides the least risk.
I've never agreed with a post more than I agree with this one. You took the words right out of my mouth, and then wrote them more eloquently.
Wad it up. You get more surface area and can apply more pressure without trouble. and the Charmin Bear agrees...
One of the main reasons I don't enjoy the fold is because you can feel the contours of your hand/fingers through the fabrics in all the wrong places.