I used to believe as you do that if you faithfully involve your general in every battle (in heroic deeds not just chasing routers) that he would naturally improve and it was the long, necessary process of building that super general. I was really annoyed yestaerday as I was playing a game as the English and had been training a royal knight general up on rebellions in Wales and Scotland. He had fought about 10 battles, winning every one and killing many, many men in every one - infact the last three battles he had fought on his own against 1 to 3 units. After the last battle he got the "not so bold" vice....... -2 morale for being a coward! He also never picked up any virtues. I am confused. I would also have been angry, was it not for the fact that the next turn I built a feudal sgt unit with 5* command and natural leader virtue.
Maybe the game felt guilty!!