28 Tex. Admin. Code § 3.8014
For adult admissions, the recommended length of stay is between 14 and 35 days, with utilization review points and treatment periods, depending on the condition of the patient, accompanied by the commencement of appropriate utilization review and discharge planning at the time of admission. For adolescent admissions, the recommended length of stay is between 14 and 60 days, with utilization review points and treatment periods, depending on the condition of the patient, accompanied by the commencement of appropriate utilization review and discharge planning at the time of admission. The utilization review points referred to in this section shall be based on criteria addressed in § 3.8012 of this title (relating to Continued Stay Criteria for Inpatient Rehabilitation/Treatment (Hospital or 24-hour Residential) Services).
28 Tex. Admin. Code § 3.8014