That's highly unrealistic, but review alone would take at least twice as long, since the average video length is about 12 minutes.
How would you find out in just 5 minutes whether a monetization claim is justified? Not every case is as clear as the piano teacher's case. Keep in mind that this isn't a DMCA takedown request either - it's about a party that claims the content in order to redirect the revenue.
So you seriously claim that on average you can find out in just 5 minutes whether one of the 6 license types [0] applies and the claimant actually has a case? If it was that easy, I doubt that court cases like [1] would take years. And that's assuming all the information is already at hand so no further communication with either party is required...
[0] https://www.bmi.com/licensing/entry/types_of_copyrights
[1] https://completemusicupdate.com/article/song-theft-dispute-o...
Let's say it takes 5 minutes to properly adjudicate a dispute. 5 minutes allows 20 per person-hour. An 8 hour shift could resolve 160 reviews. 7200 / 160 = 45 shifts per day to review all of the hypothetical copyright issues. I don't think that's required, and the number of requested reviews is going to be some fraction of that. Requiring google to spread out under 50 shifts over a 24 period in order to provide a fair review so that they may bring in billions of dollars a year from youtube doesn't seem like a large ask. This is call-center-esque work and even done in the US or Western Europe would be very cheap, particularly as it can avoid otherwise more cumbersome regulatory hurdles.