The auto adjust is to give a range of effects yes.
What I do , and this is me, I set auto adjust and go for a run around 2 or 3 corners, hit the brakes hard and accell hard a few times. And thats without hitting any walls and carefully going over curbs. Then I untick, test and change numbers
Thats what I do for longitudinal and lateral. Yes it gives me some harsh effects, but then I increase numbers till i find a motion I like.
With vertical bumps, I set auto adjust and carefully take of and drive maybe 500m, then I untick and fiddle with the number and percentage till I find something I like.
Then I toss in collision effects and change numbers there as I change the force numbers. Its a matter of test and re-test.
Its a personal preference thing, but I always use auto max adjust to start me.
Dirt 2 and 3 has harsh motion for obvious reasons, you are going over rough ground and really throwing the car around.
Race 07 is softer by far, with a good general road vibration in vertical.