I have been told numerous times not to cut close to the material unless I have tied off the seam as they can wriggle and eventually will open the seam. When I first started quilting I was told always use beige thread and don't worry about threads they add to the warmth of the quilt so don't waste them. I do cut back to about 1-2". I do a lot of white backgrounds and have yet to see a dark thread showing thought. I try to buy heavier whites and not those thin ones.