I'm a newbie, so please take it easy on me on my first post.

I've read a lot about how curve-fitting a system is bad, and I can definitely understand that for a static system whose rules don't change, curve-fitting is a disaster.
However, if you design a system that adapts over time by adjusting a few key parameters, in theory you can adjust to changing market conditions and perform a lot better.
In essence, you are dynamically curve-fitting, and on paper you can come up with some great looking systems.
Is this basically just as bad as curve-fitting in a static system whose parameters don't change? Or is this even curve-fitting at all? Or does it approach curve-fitting when the system can adjust itself too quickly, but it is not so much with a longer time constant?
This is the kind of thing that I can test and test, but it seems to go against conventional wisdom. Any advice?
Thanks!!
Samir