OK, thank you.
I know about the differences in human perception and real behaviour of light, but I did not know about that video, it is greatly wellcome.
But as you point, I am not so sure about when to use something that mimics light behaviour (lineal) or human perception (LAB of gamma compensation).
You say that each module does the needed transformations from the workgin space you select in input profile and the model space it uses to do its magic and then back to the working space.
So you should be able to use a color correction module that is design to work in LAB to improve contrast without altering colors, for example.
You should be able to use that module with similar results with a linear ProPhoto working space, an sRGB space or AdobeRGB or Rec709 (as long as you do not produce out of gama colors).
But for example, when I use the exposure module (in the current implementation it seems that it works in a lineal space) results are different if I select a linear space or a gamma compensated one like sRGB or AdobeRGB.
If that modules converts the pipeline to a lineal space internally the effects should be similar.
Are there modules that expect a fix working space (lineal space for example) and do not make that internal convertion?