I promised some choice words to scene directors on the IRC. So there they are.
Please, for the love (life) of the Kyon, stop putting the position parameters (at clause, ATL) to the every. single. damn. show statement!
That is reeeeeeeeeeeeally unnecessary, as Ren'Py is smart enough to show the image in the place previously occupied by the image with the same tag (first word in name) as one is going to be show, by default. So, at clauses (and its ATL equivalents) should only get used in first show of that image family in the scene or when moving sprites around. NOT ALWAYS!!1
Current situation makes shuffling sprites around while keeping scene consistent rather tedious. So, please, change your ways, for everyone's sake.