QTR-Quadtone RIP

Hello,
I am using MIS UT7 inks in an Epson 4000. I am attempting to make some 
curves for this combination and my chosen paper. I find starting with 
the 2200 UT7 curves, that the Light Black ink is not used. I would like 
to use this ink (why let it not be used?) since I feel using the larger 
number of inks might make a better tone. For example, the warm tone 
curves only use Black and the two tones of warm grey (Cyan/Light Cyan 
positions in the 4000). Only three inks being used. Why would the Light 
Black ink not also be in play? I am trying to do this without a 
spectrometer - and scanning/PS color sampler tool is a difficult way to 
go. 

Has anyone created a curve using the Light Black that I could use as a 
baseline for some creative curve making? 

thank you,
Ken Smith