If there is already some technical info on this, please pardon my ignorance. Quick google search turns up some superficial articles, but not to the depth I am interested in.

Obviously even in this little system there is a whole host of potential variables...port diameter, diameter of adjustment screw, how far the screw turns each "click", gas system length, caliber, and so on.

I'm trying to figure out how much adjustment makes to "flow".

All the way in is zero of course, but at what point does turning the screw out stop doing anything? From experience it seems that one click (1/4 turn of the adjusting screw being standard?) is generally the difference from not functioning properly, to at least proper function, if not more than enough pressure, with the same load.

Is "one click" on a gas block generally (every manufacturer probably having different ideas) a pretty small adjustment, increasing the opening far less than port diameter?

Just for background, in my case I have a 16" barrel with mid-length gas. With the gas block three clicks from fully seated, I have proper function with every load. But does that mean I have a bunch of pressure left to tap if I needed to for some reason, or could I be one click away from "full open"?