Did gladiators really train for a specific master like they do in the series? It seems to me that this type of training would be more suited for soldiers, not indentured servants/slaves. Was gladiatorial sport a financial endeavor, or more of a criminal sentence like it is represented in other films?
As a follow up question, there is a character in the show who sold himself to Batiatus until he earned enough money to pay Batiatus back, in order to feed his family. How common was this practice?