For indicators yes, you can set parameters as you like. But I was talking about parameters found within the price movement itself.
What you are describing appears to be your own customised indicators. Any function or identifiable feature of price history and volume is an indicator, even a logical function that says buy, sell, hold or wait. Having trading rules as a parametrised function gives scope to select the parameters to optimise gains over a period of past data. That doesn't guarantee future success of course.
The principle is simple and you haven't described anything new.