I've gone a bit off-topic myself, if the topic was sharing GCed materials. Getting back to that, I'd like to be reasonably sure that what I'm sharing is going to be a "Valid Shader". By that, I mean: something that closely approximates what one can expect to find in the real world.

If that sounds lofty, one of the reasons I continue to struggle doing maths (starting with understanding them) is because of the concept that materials can be mathematically represented.

All this is not easy for me. I agree that I tend to run questions into each other which makes it hard to decipher what exactly is being asked. I will endeavour to isolate a question from other questions in order to facilitate a response.

Note the word "endeavour".

Assumption: all colours that end up in the diffuse_color and alternate_diffuse channel need gamma-correction before processing.
Question: do colours used in nodes that get plugged into specular channels need gamma-correcting before processing?

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks