This paper develops a model to explain recent trends of work intensification and employee burnout. In an organization a manager assigns tasks to an employee; doing tasks is costly and too many create burnout. In a matrix-style organization, different managers simultaneously assign tasks to an employee, ignoring the `externality' their directives generate on the overall productivity. An over-assignment of tasks also occurs in a vertical hierarchy when task managers at different levels can directly assign tasks. These two frameworks provide a theoretical foundation behind empirical trends and generate testable insights on the organizational causes of burnout.