I'm trying to optimise the image sizes for Wordpress and notice that the Twenty Twelve theme has a 625 pixel max width, so I may as well make the "large" size 625 pixels wide as if it's larger them Wordpress simply scales to 625 anyway. Having a larger image that is scaled down just means slowing down page load time as the larger images are loaded. Just noticed that the page rank for this site has dropped from 16,735,342 to 7,634,857 in one day which is not too bad considering I get less than 10 visitors per day.