For an employee seeking intermittent leave or reduced schedule leave, what is meant by the “medical necessity for” such leave?

what is meant by the "medical necessity for" such leave? (See 29 CFR § 825.117) (a) For intermittent leave or leave on a reduced leave schedule, there shall be a medical need for leave (as distinguished from voluntary treatments and procedures) and it shall be that such medical need can best be accommodated through an intermittent or reduced leave schedule. The treatment regimen and other information described in the certification of a serious health condition (see section 31-51qq-31 of the Regulations of Connecticut State Agencies) meets the requirement for certification of the medical necessity of intermittent leave or leave on a reduced leave schedule. Employees needing intermittent FMLA leave or leave on a reduced leave schedule shall attempt to schedule leave so as not to disrupt the employer's operation. In addition, an employer may assign an employee to an alternative position with equivalent pay and benefits that better accommodates the employee's intermittent or reduced leave schedule.