"He who marches out of step hears another drum." ~ Ken Kesey
I have two most used methods if getting an underbase.I tried both and one was totally solid straight out. The other had about about 90% anywhere it had halftones. Now, I could then adjust it so that it was more open, but to me the art reads that it should be solid. This could also be a case where the last print didn't look like the original art was to be, but was ran anyways and customer was happy with it. Happens often.