Technically, the gutter on the default columns for the text area will fall into a fold using 3 columns. The fold will be slightly towards the fold on the outside and inside of the folded in panel. I prefer centered text areas (usually) and so design accordingly. And instead of the new columns, I would use separate text areas...but that's me. I also have traditionally done that in page layout software capable of frames with columns. It is less fiddling around for me.