The failure of the tax assessor, board of equalization, or the Department of Revenue or its agents to perform any of the duties of assessing and valuing property or hearing objections to assessment valuations, at the time prescribed, or to complete such duties within the time prescribed by this chapter, shall not invalidate any assessment or any act of such tax assessor, board of equalization, or Department of Revenue or its agents made or done after the expiration of such time. The duty of the tax assessor to inspect and examine real property in his county is directory, and failure to do so shall not invalidate assessments and valuations made by the assessor or the board of equalization or the Department of Revenue or its agents.