Here's a twist I don't think I've seen before: My aim point is mid-way between Grade 2 and Grade 3 instead of the traditional Grade 2.

I defined this by setting my upper and lower control limits by picking a negative that printed properly on Grade 2 with a moderate amount of burning, and a negative that printed well on Grade 3 with a little dodging. Naturally, I want to have my aim be in the middle.