this is actually what I see and which explains why with a single base stone and different nagura (assano for example) then a tomo you can go from start to finish without anything else.A few months back, @SliceOfLife made the point that not all slurry is equal. Thuri slurry is more about cushion and less about abrasion. Coti slurry is a lot about abrasion, which is why many rinse all the slurry away before finishing with water.
My guess is that not all JNAT slurry is equal and that some continues to cut more than others, and that you just need to adjust accordingly.
But the question remains