I think that 2 minute periods is not enough to get a feel for much. Penalties especially.
But in regards to penalties; you won't see many unless you are hitting the buttons that cause them. I call the lift stick button the "penalty button". That and poke checking cause the most penalties for a human. Other than going around and just hitting people for no reason you won't see much. There just are not that many penalties programmed into the game still. And you have to be super aggressive or have players with bad ratings to see them occur.
As for the CPU taking them. Once again you have to give the AI a reason to take one. Play keep away, set up in their zone for a long period of time and make them get tired and scrambling out of position. With 2 minute periods that is hard to accomplish. That and the fact that most people just come flying into the zone and make a move and shoot. That does't give the CPU a chance to take a penalty or the desperation.
All of that doesn't take away from the issue that the sliders really don't work in this series, historically speaking. And increasing the penalty slider doesn't seem to increase the likelihood of penalties being called for most people.