Softer, low alloy carbon steel blades need a coarser polish than harder higher carbon Japanese carbon steel to enhance durability and edge life. Like with all knives good edge geometry is crucial and coarse stones will help provide that shaping work.
Keep in western carbon steel knives benefit from periodic edge maintenance with a sharpening steel. Feel the edge in an outward motion (away from the edge) to feel for a slight bend on the edge; one side will feel smooth and the other a little rough, this is the time to use a steel. Stones are essential to preserve ideal geometry in tandem with regular steeling.
For carbon steel boning knives, we recommend a coarser finish from medium stones -- 800 to 1200 -- for a more durable, bitey feel deburred with borachrome on a strop. Jinko Aoto (2000-4000) and Naniwa 2000 for are great chef knives, slicers and scimitar/bullnose. De-burr Jinko Aoto or Naniwa 2K finishes with the chromium oxide on a cork strop.
Remember that sometimes a coarse stone is necessary to re-set more heavily dulled (or rounded from a steel) edges, if your edge has rounded or it takes more than 5 minutes to get a burr with a medium stone then a coarser stone is in order.
Diamond stone flatteners are best to quickly level out the widest range of stone grits. Some flatteners can leave behind large particulates on medium and finer stones that can leave deep, unexpected scratches. Use your fingers to feel for any malignant grit that needs to be cleaned off.