Contrast ratio

I think that i asked something about contrast ratio time ago yet and if i remember correctly the general idea was that experienced cinematographers like you perhaps use more the eye and the instinct than a formal math formula. But for me is still an useful starting point.

Now, this said, i noticed that It’s easier for me to achieve a given contrast ratio by increasing the key light instead of  decreasing the fill light with negative fill for example, then lowering the exposure in post production to achieve the right look. Since It’s a ratio Is the range between Key and fill that matters, and i would still obtain it (but i would need to correct It to obtain the right look of course) and i could control in a better way the noise in low Key scenes. Perhaps achieving the right ratio from the start directly in camera Is the best option, but as a decent alternative this approach seems easier to control (at least for me). Is it a good approach?