When you said earlier it was notorious for adapting, I thought you mean it in a bad way because of the word notorious. I thought something like after it has adapted, the power increment is not there anymore.
It works by having a fixed set of parameters.
Say the A/F is set to be ideal at 14 (for example). Your fuel is electronically controlled and you install a high flow air filter. So now your A/F is suddenly leaner to perhaps 11. The VDO will detect the difference and to compensate, it'll pump in more fuel to get the ratio within its set parameters.
In this sense it's a good thing.
But take those air leaker devices for example. Changes the internal vacuum or pressure or whatever and results in a better performing car for whatever reason. VDO detects the pressure is out of its parameters and normalizes it by counteracting with something else (I don't know what). This effectively means your device is made redundant.
In this sense it's a bad thing.
Kapish?