I think periodic training and rotation of auditors is required to enhance their interaction with other professionals and practitioners. Moreover, pre-audit and post audit meeting with concerned stakeholders and departments could equip the auditors to reduce or eliminate differences. In addition, local and global exposure with diversified work settings could help to address the differences in results.
Every audit firm should establish a system of quality control designed to provide it with reasonable assurance that the firm and its personnel comply with professional standards and regulatory and legal requirements and that reports issued are adequate in the circumstances. Each firm should ensure that its quality control procedures are adequate, relevant, operating effectively and duly complied with. A monitoring team could be put in place for this purpose. That way, the differences in results could be reduced or eliminated.
First of all, there is a need to identify the differences between 5S audits and ISO audits and then the impact of using these two different approaches.