The instances in which I used dilute Dektol in conjunction with half-tone film is to give me a low contrast unsharp mask (positive of my camera negative) that I then print in register with my camera negative. The net result is to increase apparent sharpness on the print due to edge effects and to compress the contrast range of the camera negative by an amount equal to the net peak density of the mask produced. I then use additionally masking to expand the local contrast of either/both the highlight or shadow portions of the print which are located on the "toe" or "shoulder" where the slope is not nearly as pronounced as the straight line portion of the characteristic curve.
I have also used A-B developer at times when I want higher contrast from my masks. I have samples of new lith film coming to me for evaluation in separation masking of the camera negative into three distinct density ranges so that I may print these ranges (shadow, midtone, and highlight) at the appropriate contrast setting using variable contrast materials. In other words, I could print the shadow and highlight values at a grade 5 setting (for instance) and the midtones at a grade 1.5 (for instance). The tonal separation on the print would then be more straight line and this would quite effectively bypass the limitations of the characteristic curve of both the camera film and the printing paper.
Any thoughts that you may have regarding this process would certainly be welcome.