Ok then, I guess your issue was knob twiddling of color heads, which may be used successfully by projecting white light onto graded papers (i.e., no adjustments of any kind being necessary), versus using separate filter gels for contrast under white light of virtually any head type for VC papers. Thanks for the clarification.
My main point was about exposure time for highlights when using colour heads for changing grades compared to filter gels. In my experience the colour heads can cause highlight times to vary significantly compared to using the gels. This meant more time to make a good print, more test strips and more wasted paper which is why I now stick with the multigrade gels.