Having multiple management systems requires increased time and resources for their maintenance.

In some cases, each of the standards will be implemented by a different person, so the systems may follow different logic or structures.  Also, the documents and processes are often structured differently, which can bring additional complexity to an already complex system. 

Having multiple management systems can easily become an organisational nightmare.

Instead of contributing to the improved performance of organisation, they become a burden that everyone avoids, and the standards are only implemented as a formality, without any real benefit.

An alternative to this is to have one Integrated Management System that meets the requirements of multiple standards and simplifies the maintenance and coordination of many activities.

The latest revisions of the standards for 9001, 14001 & 45001 include many common elements that make the integration mush easier to achieve.