Never heard that one before. I look at it, leave the room for awhile and come back and look again. Then I leave it for a few hours, check it again. If I'm still pleased it is a go.
That's how I do it, too, and sometimes it takes a week of this to get it right. I lay out on 2 twin beds with a cardboard between them, and it always helps to look at it from different sides. What looks fine one way may not be so great the other. That's the advantage of not using the design wall, too. There are fabrics that change color from different directions and you can spot them that way. Once I used a medium dark aqua blender that actually looked like a black hole from the other way - and I didn't spot it until after it was embedded in a big group of blocks.