Fold - to neatly wrap the toilet paper around hands or fold it up in such a manner as to not risk losing chunks of the toilet paper in the bunghole.
Scrunch - to hell with neatly wrapping, you just wanna get the shit off of there.
Personally, I sit initially, while wiping, in order to make sure any dangling turds don't end up in my pants, and then I stand. Always scrunch though, never had the patience to fold. Also, I can't stand underhand toilet paper setups. They HAVE to be overhand. Otherwise I
refuse to use it.