We know you can do
if ( is_singular( 'my-cpt' ) ) to test for a specific custom post type, but what about doing one thing if the post is a built-in post type, and another if it is not?
Is it enough to just test against
if ( is_singular() && ! is_singular( 'post' ) )? Or are there some implications or subtleties that are escaping me at the moment?