What you are training
A monitor mix is not a smaller version of the house mix. The singer needs their own voice and the instrument that gives them pitch, and almost nothing else; the drummer needs kick, bass and a little vocal; the guitarist wants less of everything except themselves. A good wedge mix is sparse, and a bad one is a wall of everything that makes the stage louder and the feedback ceiling lower. This drill hands you a monitor request from a musician and a set of sends, and asks you to build the mix. The scoring rewards restraint and the right priorities, not a full fader board. Five rounds walk through the requests that come up on every stage, and show what an experienced monitor engineer would have sent instead.
After this drill, the plan: The daily plan drills the vocal wedge first, then the drum fill, then the whole stage from a single console.