A question: The altering, would it be more glycerin for areas of less humidity or less glycerin?
You can use more glycerin if you are in an area of low relative humidity. Using too much will result in prints that feel a bit damp. At one time there were several commercial products such as Pakasol and Edwal Print Flattener.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.