Whenever any resolution, order, notice or determination is required to be published or posted, and the duty of posting or procuring the publication or posting of the same is not specifically enjoined upon any officer of the City and County, it shall be the duty of the Director of Public Works to procure the publication or posting, as the case may be. No proceeding or step herein shall be invalidated or affected by any error or mistake or departure herefrom as to the officer or person posting, or procuring the publication or posting, of any resolution, notice, order or determination hereunder when the same is actually published or posted for the time herein required.