tourist visa in case they are tourist METV in case they are frequent travelers as tourist. Or any other visa that qualify their status. Even if only for 1-2 days at a certain point the IO will recommend to get a visa.
the extension is not a requirement but an option. As long he qualifies for the visa and he is happy to pay every 3 month the embassy will issue a new one.
i understand your point and was actually my intention that time but if you go for it and the person that need to cancel it refuse to do it and say it is not needed there is nothing more that you can do
i did it with non O after that and no issues. The day i went to immigration try to cancel the non B extension the IO told me it will be cancelled automatically once the WP letter cancellation will be issued and even if i believe that your mentioned procedure was correct i wasn’t on the position to argue about it, but so far no issues after that. Maybe could be an issue if asking same category visa (non b) in the future, this i don’t know