>For S-curve adjustments i usually just do a rote formulaic >approach where i apply a pull down point near the lower left >and a push up point near the upper right.
No. You have a fixed amount of contrast to allocate over the whole dynamic range of the image. You want to put it where it does the most good.
Load a Curves layer. Find the object(s) of interest in the image. Ctl-Click (PC) on the darkest element of the object of interest. This will place a control point in the curve. Pull down to taste. Find the lightest element in the object of interest. Ctl-Click and move up. You have now placed the steepest part of the curve so as to maximize the dynamic range of the object of interest. (A "standard" S-curve puts this in the midrange, which may or may not be where you want it.) (I do this in PS. I assume it works in CNX2.)
Before you do this, correct the dark and light points to fill the dynamic range.