What disadvantage is commonly associated with Parallel Running?

Parallel Running involves running both the old and new systems simultaneously for a certain period of time to ensure that the new system performs correctly before fully transitioning to it. One of the main disadvantages of this approach is that it requires significant resources. This includes not only financial resources, due to operational costs incurred by maintaining two systems at the same time, but also human resources, as employees may need to manage and monitor both systems concurrently. This can stretch the capabilities of the organization, potentially leading to resource allocation issues and increased complexity in daily operations. Moreover, the management of data across both systems can add to the administrative burden, complicating processes that would otherwise be straightforward if only one system were in use.

The other options, while they have their own implications, do not capture the core challenge of Parallel Running as effectively. For instance, while user training needs may increase, this is generally related to the complexity of the new system rather than the method of implementation itself. The risk of data loss and limited user feedback are also considerations but are not as directly linked to the resource-intensive nature of running both systems in parallel.