Your question is not well framed. You might want to try a new poll, as it looks like this one is just starting. Here is why.
Whether I shoot RAW or JPEG, I choose a PICTURE PROFILE/STYLE that already has less saturation.
Either in camera or in Lightroom, I pick a Picture Profile (Landscape/Portrait/Faithful/Natural/Etc.) Then I adjust teh saturation settiings in camera or post to reduce saturation.
I also shoot in AdobeRGB, not sRGB.
So THERE IS NO STANDARD "SATURATION BASELINE" to reduce from. It depends one the profile and color space you are shooting in. There isn't a number that applies to all.
I shoot Marvel Cinestyle, Technicolor Cine or ProLost Flat.
http://prolost.com/blog/2012/4/10/prolost-flat.html
ProLost Flat starts with Natural, and then sets Saturation to -2. So in a sense, -2, but that is much different than "Landscape -2 sRGB."
Sorry, I didn't mean to shout.
I just wanted to emphaisze that there is no "Saturation" benchmark, like Greenwich Mean Time, that eberything can be compared to.
Cheers!
Michael