Multi-project management is vastly different from single project management. A single project manager is responsible for only one project integration, scope, time, cost, quality, human resource, communication, risk, and procurement. A multi-project manager is striving to manage all of these for more than one project at the same time. In most of the cases, the projects are in several phases, with different requirements, and diverse objectives. The senior management expects every project to be equally successful by meeting the allocated time, cost and budget.  Management want to have:

Traditional critical path project management is incomplete in addressing these challenges and is missing the multi-project perspective on how to resolve conflicts, balance requirements, prioritize resources, and maintain alignment with the organizational strategy.  The reason why critical path based approaches struggle with multi project environments, is because the critical path keeps changing as the project progresses. Since the critical path keeps shifting, managers struggle to:

Critical Chain excels in multi-project environments but multi-project management is also the point at which strategic management and project management interact. Because if the strategy of the organization is poor to begin with, will it really help to get the wrong products completed faster?

Remember projects are undertaken to bring benefits to an organization, the sooner they are completed, the sooner the benefits are realized. Critical Chain focuses on reducing the time it takes to complete any single project. In a collection of projects, Critical Chain focuses on the factor that most effects the cumulative cycle time of all the projects. This factor is known as the organization's strategic or critical resource, also called the "Drum". Critical Chain's focus in multi-project environment is on the critical resource in order to improve overall project performance.

Why is knowing the "Drum" resource so important within the multi-project environment? As we said the biggest factor impacting cycle times is the resource bottleneck. Because we know from a number of studies that most organizations try to push more work (in the form of new projects, etc.) into the organization, irrespective of the capacity of the most critical resource - the one that most impacts the cycle time of all projects. It is thus vital to educate at the executive level in order to eliminate the constant release of new projects when key resources are not, available.  Typically executives release projects into the system to meet their quarterly or annual targets on which their bonus are calculated and they can be quite demanding on getting resources for "their" projects. Different executives and managers make conflicting demands on resource managers. The resulting compromise in most organizations is multitasking of resources - people working on multiple projects simultaneously.  Multitasking of resources, especially those on the critical chain has the following impact:

When multitasking all three projects are delivered later than would have been possible when staggering projects sequentially. 

Resource levelling is greatly simplified due to the multi-project Critical Chain practice of staggering the introduction of projects into the system according to the availability of the strategic resources, "Drum", of the organization. This results in the reduction of bad multitasking and of the number of active projects in the entire organization at a given point in time. More projects can now be delivered in the same time period with the same resources.  At this point in time it also becomes possible to prioritize projects objectivity, which is based on which projects are best for the organization, rather than on which executive shouts the loudest.