Amount and size and location varry so much from one class of bait, one shape of bait, and when made of wood one bait to another, that I sure could not give you any formula. I think I know what weights you are using, and they are a good start, but I don't use them.
Most of the time I will drill a hole and use #9 lead shot. It takes a larger hole then if you used the solid weights you mention, but it allows more flexibility.
One other thing I have done is to make a mold out of Silicone mold putty. Yes, you can pour lead into that mold and get quite a few before it goes bad. I take different sizes of wood dowles and push them into the mold putty to get the depth and width I want.
I hope this helps some. I am sure there are others here that have great ideas on this as well.