I noticed that creating twentythirteen-child/archive.php overwrites twentythirteen/archive.php but creating twentythirteen-child/shortcodes/drop-cap/drop-cap.php does not overwrite twentythirteen/shortcodes/drop-cap/drop-cap.php.
What does this depend on? Sub-folders aren't overwritten?
Similarly twentythirteen-child/shortcodes/drop-cap/drop-cap.css will not overwrite parent CSS file if called through
wp_enqueue_script();. This means that
wp_deregister_script() must always exist for multiple CSS and JS files (and for PHP files in folders)?