Not sure if posted but I go through nail files more than anything else. The kind women use on their nails. One set is 80 grit on both sides. One set is 120 one side/240 other side. I like using these over sand paper because the foam in between the grits gives it more structure, kinda like using a block, but with enough pressure curves to the bait. Kind of hard to explain but steal some from your girlfriend/wife and try it.
I start with the 80 grit till I like the profile then hit it with a couple passes of the 120 before ending with the 240. Works really good on lathe baits too. Usually get a couple/few baits per file before throwing away.