I can completely understand operators requiring checkout dives in whatever guise they happen to be. Personally I would take it as read that at least one dive on any trip with a new operator will be a checkout even if not named as such.
You could have a diver that has just finished OW with better skills that an instructor with 100's of dives. How? The instructor maybe hasn't been in the water for months, did his teaching using overweighted students on their knees for skills etc whereas the OW student might have had the best instructor who insisted of full mastery of everything.
As someone above said, skills are a practical thing and if not practised can get rusty pretty damn quick. The only proof that a DM has of skill is by seeing it in the water with their own eyes. They can then do a risk assessment of who can dive with minimal supervision and who is a FIGJAM and needs an eye kept on them just in case.
You could have a diver that has just finished OW with better skills that an instructor with 100's of dives. How? The instructor maybe hasn't been in the water for months, did his teaching using overweighted students on their knees for skills etc whereas the OW student might have had the best instructor who insisted of full mastery of everything.
As someone above said, skills are a practical thing and if not practised can get rusty pretty damn quick. The only proof that a DM has of skill is by seeing it in the water with their own eyes. They can then do a risk assessment of who can dive with minimal supervision and who is a FIGJAM and needs an eye kept on them just in case.