Final answer:
The hours an employee may engage in incidental secondary employment without formal approval is not specified and may be subject to company policy or regional labor law. It is recommended to consult with one's human resources department for such details.
Step-by-step explanation:
The question relates to incidental secondary employment and does not specify a universally applicable hour limit, which suggests it is likely referring to a policy specific to an organization or a study case. The primary reference provided mentions different scenarios such as a guaranteed income and the choice between leisure and work, embodying concepts like the Poverty Trap and income effects on labor supply decisions.
However, as the exact figure for hours of incidental secondary employment that can be engaged in without formal approval is not provided within the context of the given references, and may be subject to company policy or regional labor law, we cannot definitively answer this question without that specific information. Employers often set their own policies regarding secondary employment, and so it is recommended to consult with the human resources department or a supervisor to clarify this matter within your own place of employment.