The August 2006 TOC Update from Goldratt Marketing Group includes an item on The Impact of Multitasking by Mike Mannion and Sven Ehrke.
Remarkable as it may seem, traditional project management regularly fails to include explicit account of resource conflicts in its schedules. It is extremely common, for example, to find workers implicitly assigned to tasks on two, three or more projects simultaneously.
This is multitasking. The authors use familiar (to TOC practitioners) discussion elements to describe the detrimental effects of this common practice. Namely, projects are delayed.