If we want to have different template suggestions, such as based on url alias, we do so in preprocess function of that hook (you can use _block, _page,...)
<?php
function yourthemename_preprocess_page(&$vars) {
$alias = drupal_get_path_alias($_GET['q']);
if ($alias != $_GET['q']) {
$template_filename = 'page';
foreach (explode('/', $alias) as $path_part) {
$template_filename = $template_filename . '__' . $path_part;
$variables['theme_hook_suggestions'][] = $template_filename;
}
}
}
?>