Random luck and lot of gold play a role in infiltrator training. You need a good financial backer(Hint, Duke currenlt) to help you with gold for training. Ultimately the random luck in skill increment, either you roll good head coin(increase) or bad tail coin(maintain). You can try keep track of your skill and see whether it improves with longer hours training or shorter hours training. Try average your hours, see this make a difference or not.
