I'm not sure if this is on topic, but here goes.
Cyan in RGB is (00, FF, FF). Red (or green or blue) is this (FF, 00, 00). So this seems like if I tell my monitor to display cyan, each pixel will have 2 subpixels fully activated. If I tell my monitor to display red, it will only have one. So a monitor with a peak brightness of 300 nits would only display 100 for red and 200 for cyan.
Cyan in HSL (or HSV, is there a difference?) has a hue of 0.5, saturation of 1, and a lightness (or value?) of 1. Red has a hue of 0 (or 1, these are identical, right?), saturation of 1, and a lightness of 1. These both have a lightness (or value) of 1, so the 300 nit monitor displays 300 nits for both colors.
So which (if any) is right? The second one makes sense to me, I wouldn't expect cyan to be any brighter than red, but I can't figure out why the first doesn't make sense. Am I describing color completely incorrectly?
As suggested, I'll edit to include how this affects my workflow. Short answer, it doesn't. But I think understanding color in general is very important to an art which is literally just capturing color on an xy grid. If I had a question about how the aperture actually opens or closes on a lens, I'd ask that on a photography network, not an engineering network.