That's the general idea but it's not perfect. LC varies a ton with speed due to the thicket diameter. I don't even know what brand of LC I have, but 8 feet per color seems pretty ambitious. I find at the typical 2.5 - 3.0 summer trolling speeds, 3-5 feet additional depth per color. I don't like running out 300 feet of line so we add additional inline or snap weights to get deeper than the 5 colors I spool will go. Best thing to do is just run to a depth you're looking to hit and see what it takes to tick bottom and calibrate things yourself rather than trying to guess based on the charts.