How to ruin a photo

Hi Martin,
It may not be necessary to use Lab in almost all retouches.  It's hardly ever mentioned in tutorials on retouching.
However, I find it a lot easier to use than the RGB curves.  In fact, I find the RGB curves to be torture to make large changes in tonal value or color.  The big advantage of the Lab Curves are:
1.  Color and lightness have been separated.  That mimics human vision.  The human eye converts the RGB sensor signals to Lab and then sends Lab signals to the brain.
2.  It's a simple matter to increase the range of tonal value and the range of color intensity without any interaction between the two.
3.  Photopaint has a "linear" mode which I like.  The curves do not bulge out in unexpected places.
4.  You get four primaries instead of three if you pin the center  of each curve.
5.  For instance, this means that you can increase or decrease blue without affecting yellow or the Lightness.  That can't be done in RGb Curves.
6.  Thus you can use a heavy hand in Lab when changing color.
  There is an entire book by Dan Marguiles on the Lab mode.  Unfortunately, it is difficult reading for no good reason.  Lab is far more intuitive than RGB because that is what our brain "sees".
Phil
PS:  Here's an example.  This one could have been done with a Color Replacer tool.  However, Color Replacer tools will replace a range of colors with a single hue. The Lab Curves shift the entire spectrum.  (They only maintain the range of Lightness.)