[RodB]

Keep in mind we don't really know what values the engineers came up with. All we see is what is on the drawing and what is inside the chassis. They used the closest component value to what the calculated one was, plus the parts manufacturers couldn't get much closer than 20% for standard parts. It's evident that cost often determined the final parts placement (what do you mean I can't add fidelity?). So this is why I use 10 percent tolerance. Plus, it's easy to calculate.