I think it does.
Why do we have the screen? The screen is there so the Prime Minister can function and doesn't have to constantly think, “Can I do this or not? Do I have to recuse myself?” In effect, it's to allow him...so things don't come to his desk that he can't handle. They're handled beforehand. They're being kept away from him so he can freely make his decisions. When there's something that causes a conflict, somebody else makes the decision.
Who administers it? It's the chief of staff and the Clerk of the Privy Council. Both of their jobs are to protect the Prime Minister. If they don't protect him and they let something through that causes a conflict of interest, their jobs are on the line. It's in their own self-interest to make sure the screen works and is as tight as possible.