Boy that Rayburn guy must of paid attention in geometry class. His teacher would be proud. Little did we know back in school that this math stuff would come in handy later on when building lures.
I like do the dunk test to find out about how much ballast is needed. I also add the extra hardware ( hooks, clevis or what ever I might use in the build) for the dunk test. It can make a little difference especially if I'm try for neutral bouyancy. However I don't try to get exact with the weight as the water temp and line type will impact how far the lure will sink or float. Mono size/ wt is different from flurocarbon lines how deep a lure will go. Then there is body shape, bill size and angle. The factors go on and on. I get it close and go from there. Once I get the weight needed and do a followup dunk test after installing the ballast to check that the lure does what I want it too. Sometimes to get the right lure attituted (nose up, down, level) I will drill more than one hole.