I used to shoot for having realistic penalty totals during games, but I've realized that the penalty sliders do much more than that. They alter the tendencies and aggressiveness of players in game. In fact, sometimes they have more of an effect on the game than the gameplay sliders do.
So, I now use the penalty sliders as tendency modifiers. I see a few penalties a game, enough to remind you they happen, but no, they are not realistic amounts.