There was lots of talk awhile ago about the poor results from multitasking. Afterburners is a training organization we've participated in before. At PMI conferences and on a government contract. They can speak directly to multitasking and task saturation in a group setting. These concepts go directly to the management of projects.
Avoiding Task Saturation
Plan the work, work the plan is a starting point. But is the plan credible? Is it executable? Are there enough resources for success? What are the impediments to success? The answers to these questions must be in the Plan. The Plan is the strategy for project success. The Plan is not the Schedule. That's separate. The Schedule shows the sequence of the work that must be performed for the Plan to have a probability of success. Notice the work Probability of Success. All Plans must adapt to the emerging situation.
Subscribe to the Afterburner feed, you'll get great project management advice, as well as business management advice. Stop listening to the "red herring" thought leaders who tell you that the source of the problem is Waterfall, or multitasking, and what ever. And start taking action to be successful.