Well, nothing drastic, but this is what i use.
Test matches.
1st innings - start with 4 aggression bars/field bowl default line and length until batsmen reaches 20-25, then use 3 aggression bars and bowl to weakness. If they hit two fours in an over, or reach 35-40 bowl the other side of the wicket.
Once they reach 50 drop down to 2 bars, rinse and repeat above really, once 75 is reached 1 bar, so on and so forth. Sometimes, you just have to keep playing around with things.
I don't always follow what i type above, i vary it myself depending on the situation.
2nd innings, if you have a lead, and are winning the test match always start on 5 aggeression bars. Never drop below 3 if you are chasing the win.
The above is with regard to bowling only.