So I finally updated my site to responsive design. I also switched the ads to responsive design. I then picked smart sizing and put the ad on my site. The ads showing for desktop are small rectangles like the shape of a leader-board. It seems to me that 300x250 or a 336x280 would work much better. Should I trust them that they'll pick the best ads? Or is it set up to automatically fill up the whole width without trying to figure out which ads perform the best?