Tough to answer, David, because the application of color boost is so  subjective.
best I give you an example of how I apply Smart Color.

1) See screen snap 209: I turn off the automatic SC in RAW.
My reason has to do with possible shadow noise with my camera, and boosting sometimes exacerbates the background noise.

2)  DeHAZE is certainly the same as the old Clarifier in Photo Shop....
See screen snap 210... Mike broke this down for us years ago.
Try these settings to "DEHAZE"     High Radius and small Strength, (make sure as in screen snap) that slider is at MIN

3)Smart Color....
The 1.0 that appears initially, is a multiplier...     That means if you had a shade that contained RGB.... values  the output is multiplied by 1... which is no change....  50,60,100  comes out the same.

When you apply SC automatically, Qimage reads the colors and decides how much boost the image can handle without blowing out colors.
See screen snaps 211,,, where my object was to just brighten the blue sky. (It was early morning and the sky was still waking up)
I eye dropper checked the sky color (Blue, sometimes Cyan, and sometimes both).
So selectively, I ticked the BLUE up from 1.0 to 1.4
See Snap 212
The rest depends on the image and if the image needs boost, and how much if any. Totally up to the image and your objective.

Hope some of this helps.

Fred

Thanks Fred/Terry, most useful. In general it does the right thing and I can now see that sometimes additional tweaks might be useful in Sel.Color. It was perplexing originally because even though smart colour was applied on import the Sel.Color tab showed no indication of it being applied.

David