42 CFR §409.34

1. (a)To meet the daily basis requirement specified in § 409.31(b)(1), the following frequency is required:
   1. (1)Skilled nursing services or skilled rehabilitation services must be needed and provided 7 days a week; or
   2. (2)As an exception, if skilled rehabilitation services are not available 7 days a week those services must be needed and provided at least 5 days a week.
2. (b)A break of one or two days in the furnishing of rehabilitation services will not preclude coverage if discharge would not be practical for the one or two days during which, for instance, the physician has suspended the therapy sessions because the patient exhibited extreme fatigue.