[development] Where should we call drupal_add_js?

Hi everyone, Assuming that we want to reduce the size of JavaScript transfered to the client we have some options: * always call drupal_add_js() in hook_menu() because it will be download only once to the entire site? * is there other place where we can call drupal_add_js() in a global way? hook_init() probably not because it does not get executed with "aggressive cache" I think... * only call drupal_add_js() when we are going to use some of it, in the current page? Regards, Fernando Silva