How do I create settings only used by my theme? [closed]

You don’t have to register_settigs, you can just add the options straight to the database with add_option().

You could have like a dummy option “all_pages_created” and if that’s set then don’t check for the individual pages.

if (get_option('all_pages_created') !== false) {
// it's set, do nothing }
else { // check for your pages and update individual_pages_option with update_option()
       // and when all pages are created add_option('all_pages_created', 'true', '', 'yes' )
}

Or something like that. It shouldn’t be too hard…