Well, I think it is on Dromund Kaas. When talking about someones life it usually says "he/she then went to Dromund Kaas to improve his/hers skills". Also, before they even reach Dromund they have to prove they are worth training.
Maaaybe, they apply for the job (
), they get some tasks and if they menage to survive or complete those, they are allowed to come to Dromund Kaas and train.
Oh, this is my opinion only.