Not dumb, but a fair amount of work
I do this on some common colors for which I offer choices, especially custom mixes that have become standards, like yellows, and greens and blues.
Years ago, Union's Navy was really dark, and I mixed it 50/50 with Royal to produce what I called "Cal Blue". When swatches were compared, many folks chose it over the stock Navy.
It also comes in handy when someone's artist wants a Pantone color, but I show them one of my "stock" colors which is close.