If supervising a restricted FI, the supervisor HAS to be on site, that could be in another building or inside the flying club/school but they cannot be an hour away and 'supervising'.
Like Billiebob, I’d be very interested in the EASA regulation that stipulates that...local club/school rule perhaps, but I’ve never seen it in the official books.
Like you TOO, have seen both ends of the spectrum from not being allowed to breathe without permission with “your friend and mine” to FI(R)a hardly seeing their supervisor. Like to think people are always contactable and available to be on site at relatively short notice should there be an issue but understand that a supervisor may be on a long cross country with their student... sensible and legal not always the same thing.