This is an interesting drill, however I believe the excess queens to be just that, more than 4 or so is somewhat pointless.

I would recommend that the drill be just to keep your resources below 400/400 all game and keeping between 0-25 on queens (save when you sync them) and having a queen constantly making tumors and spreading creep. When you think about it, this seems more realistic to a game scenario, and you can do this in a game with a friend. <3 :D