No. Monique is not required to prove to Shawn that her request for leave to attend active military reserve training is reasonable. Under the Uniformed Services Employment and Reemployment Rights Act of 1994 (USERRA), no limitations on an employee’s military leave of absence can be imposed beyond those required by the law (advance notice, cumulative time-in-service limit, and timely return to work). Even if an employer finds the time, duration, frequency, or nature of an employee’s military service to be unreasonable, it cannot deny the employee leave from work or refuse to reemploy the person.

Employees are not obligated to plan their military service for the convenience of their employers. On the other hand, nothing in the law prevents employers and employees from voluntarily working together to accommodate each other’s needs.

Source:  CCH When Duty Calls: Military Leave and Veterans’ Rights.