I agree that the system could be improved allowing a period of time before ads start rolling or something similar and I understand your frustration.
But currently, there is no other way to protect our music, and believe me, it gets stolen. A LOT! We are talking thousands of videos here.
If you know that a piece of music is with AdRev you can simply contact the seller and have any video / channel cleared before it goes live, or be prepared with the license details. It’s no different than entering a serial number in a piece of software you bought.
The problem is with RETROACTIVE claims but if you know a track is registered, you can clear it right away. It would actually be worse to buy non-registered music since it can be registered at any time in the future and make retroactive claims that are harder to spot.