Most, if not all, have a limit on the amount of units per day for the same or combinations of "timed" therapeutic codes such as 97110, 97140, 97530, etc. There's also the possibility individual provider contracts come into play for this.
Examples:
"A survey of the Centers for Medicare and Medicaid Services’ (CMS) Local Coverage Determinations (LCD) indicates that a majority of jurisdictions that have Physical Medicine and Rehabilitation LCDs have guidelines stating that the Commercial Reimbursement Policy CMS 1500 Policy Number 2022R0101A Proprietary information of UnitedHealthcare. Copyright 2022 United HealthCare Services, Inc.
usual duration of a therapy session does not exceed one hour. For this reason, UnitedHealthcare provides reimbursement for the codes listed below, in any combination, up to a maximum of four timed codes (equivalent to one hour of therapy) per date of service, provided by the Same Specialty Physician or Other Qualified Health Care Professional."
This is Ohio, but an example:
"Beginning with dates of service on or after April 1, 2021, Anthem Blue Cross and Blue Shield (Anthem) has updated our policy to reflect that constant attendance, timed modalities for physical therapy, occupational therapy or speech therapy are limited to 4 Units or 1 hour per date of service for the same member, by the same provider, per therapy type for (97110-97124, 97129, 97130, 97140, 97533-97542, 97760-97763)."
I have not seen any difference in outpatient OT doctorate vs. masters. However, there could be state or contract level implications.