def save_season_all_banner(self, show_obj, which=None):
        # type: (sickbeard.tv.TVShow, Optional[AnyStr]) -> bool
        # use the default season all banner name
        banner_path = self.get_season_all_banner_path(show_obj)

        banner_data = self._retrieve_show_image('banner', show_obj, which,
                                                img_cache_type=sickbeard.image_cache.ImageCache.BANNER)

        if not banner_data:
            logger.log(u"No show banner image was retrieved, unable to write season all banner", logger.DEBUG)
            return False

        return self._write_image(banner_data, banner_path)