I think this "Non-Color" procedure to be set in the "Normal Map" image node is necessary in most cases (Except for any maps in different color space) I understand 100% regarding the use of "Normal Map" and have done my tests to really check what happens.
But I am wondering if it is really necessary to set "Non-Color" space on the Black / White maps for the texture nodes "Metal", "Roughness", "Specular" etc.
I usually use jpg and png textures. This question has been on my mind for a long time, even though I see that pretty much Everywhere I look, on any tutorial, "Non-Color" is set.