For this particular exercise a Mah Jongg hand has been selected and then mixed up - so it's this ONE hand that players are trying to identify (not a variation of that hand). This is why the tiles can only be placed in a certain order.    

To read more about the drills available in the Exercise Room, please take a look at this article:   https://www.ilovemahj.com/kb/67000692163-what-is-the-exercise-room-