I started doing this recently when i've been laying out and trying to figure out what looks best. It really helps to compare differnt layouts. Once you pick the layout it helps to remind you of that layout. Keeps you from making those time costing mistakes.
Also helps keep my blood pressure down.
wildyard
I agree about look at a picture as compared to the real thing. I can stand and stare at a layout and it won't look good or right or whatever. I look at it in a picture and it seems to work or shows me why it doesn't.