I used the same natural BBW/Coticule for many years and found that the BBW side (with slurry) provided the keen-ness and the Coticule side provided the smoothness. If the blade was not sharp enough, I went to the blue side. If it needed mellowing, I went to the yellow side. I never used slurry on the yellow side until I discovered this site and began reading Bart's posts.

Since then, I have purchased other stones that have all but eliminated the need for the BBW side of my coticule but a natural BBW/Coticule can definitely be a one-stone solution.