In t20 games I tend to bowl deliveries from the bottom half of the LS. For instance, for my career leg spin bowler I don't bowl leg spin, top spin or googly very often but use the slow drift/flight and sliders a lot. It seems to make it harder for the AI to score, in fact my economy is below 4 in t20, below 3 in list a and around 1 in 1st class.