If the car is dead consistent and the "nut behind the wheel" can cut a light, there's no reason to dial soft. In fact, some guys who consistently kill the tree will actually dial ≈0.01 quicker and run it out the back door, knowing there's little chance of breaking out.
My car is fairly consistent (usually ≤0.03 from slowest to quickest pass) but I'm admittedly not so good on the tree. I dial 0.03 soft and "throw the dice" when the lights come down. Maybe I just need to step up to running on a Pro Tree! A friend is pretty good on the tree but his car ('65 GTO 400/M22) is/was terribly inconsistent.
'By-Run'
'68 Barracuda 340-S 4-Speed
11.34 @ 118.6