Area picker built inside vectorscope for skin tones

Voted. This is the exact friction, and you've described it better than I could. Mask, tweak, disable the mask, then do it again on the next clip. It adds up fast across a scene, and the new masking system made it slower rather than quicker.

I got tired enough of this that I ended up building the thing you're describing, just outside Premiere rather than inside it. It's a small macOS window you drag over the face, and it scopes only the pixels underneath: vectorscope with the skin tone line, RGB parade, and a false color mode that tints the face by how far off the line it sits. No mask, nothing to disable. It's called ToneLoupe, on the Mac App Store. Mac only, and it reads your display rather than the source, so for final QC you'd still go back to Lumetri. https://toneloupe.com

The Color announcement is probably the First Thread, but here’s a direct link for that…

You should probably get on the Beta forum as Adobe has just introduced (in public beta) a whole new color system, and Lumetri is only included as an effect for backwards compatibility. You can install beta alongside the released version with no issues and that way you can get in on the conversation of the new features. Don’t use the beta for client projects. Make copies if you’d like to try them out in the beta.

Here’s a link for the forum: Premiere Beta
And install Premiere Beta from the Creative Cloud app.