Leave under subparagraph (A) or (B) of subsection (a)(1) of this section shall not be taken by an employee intermittently or on a reduced leave schedule unless the employee and the employer of the employee agree otherwise. Subject to paragraph (2), subsection (e)(2) of this section, and section
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(b)(5) of this title, leave under subparagraph (C) or (D) of subsection (a)(1) of this section may be taken intermittently or on a reduced leave schedule when medically necessary. The taking of leave intermittently or on a reduced leave schedule pursuant to this paragraph shall not result in a reduction in the total amount of leave to which the employee is entitled under subsection (a) of this section beyond the amount of leave actually taken.