In Australia, we have associations at two levels; national and state.
The national association (Australian Gridiron Officials Association) has responsibility for standardisation on issues such as the training of officials, the production of a set of training resources, the mechanics used, the evaluation of officials, the production of the annual rules and mechanics exam, the accreditation of officials and the running of national clinics. The AGOA is also responsible for assigning officials to the national competitions.
Each state then has their own association. The state association is responsible for local training and recruiting, and for assigning officials to games. There are some variations from state to state, but generally, the state association enters into a contract with the state league (or leagues - some states have multiple leagues) for the provision of officials and the payment of game fees. Game fees are generally paid to the state association, which then pays the officials.
Formal evaluations for national accreditation are handled centrally by the AGOA. Each state association will also likely run their own evaluations. Evaluations for Level 1 and 2 officials can be handled internally by each state, but Level 3 officials need external (outside their home state) evaluations for accreditation/re-accreditation.
In my local state, the state training officer (me) reviews the video of most games, particularly on plays where some form of issue has been identified. A report is produced and circulated to the whole state association for learning purposes. Each crew is also encouraged to review their own games and produce a report, which is also available to all officials in the state. There is also a formal game report which is sent back to the league office.
We don't work in crews, due to limited resources. Most of us will have a preferred position, and a secondary position. The state assigner will try to balance positional expertise with experience in game assignments.
I'm quite happy to share privately with any of you copies of the evaluation and accreditation documents, and examples of reports and the contract, if it would help, particularly for those from countries where the game is still in its relative infancy. PM me.