It really depends on the alloy...
Lyn J. Mangiameli
>of the steel you are using, whether or not you intend to flatten backs this way (I do) and how much time you are content to spend. You can get by with this size jump if you are working the bevels of carbon steels, but it sure is going to take you a lot of time to flatten an entire back of an A2 or M4 plane blade this way.
So it really comes down to what you want to do and on what. When I flatten backs (my primary use of the Shaptons), I go 100, 200, 500, 1000, 2000, 5000, 8000, 12000 and don't find this one bit excessive and virtually essential on an alloy like M4 or All. Not only does this reduce time to flatten, but it actually is cheaper for me in the long run because I am not overworking the more expensive finer stones.
Of course, there is no reason not to start with a 1000 and 8000 and add as appropriate to your budget and needs.