The leadership does not need new moderators everyday, it's rather random and happens usually when it's running out of staff or each 6 months..etc. Making a test to see how people do and give them chances is not really what they look for.
As Mihail said, you're being tested daily and observed by current administrators, and your applications are always being discussed and anything wrong you do or good during your application period will be noted in your profile.
Just make sure you do the correct thing, and make sure you do it your own way. Being a moderator isn't for pleasing the leadership nor for showing off, it's only for helping the players and by helping them you must do it your own way, not the way people see nice so you make yourself look good.. And your way of course has to be correct.. there are plenty of guides provided when you become a moderator and can read them which will definitely help you if accepted
