Dr Bertram Miller, Md a retired pediatrician who lived and I hope still lives in Mexico was a very experience color printer. Obviously, as you may well have guessed, there was a Miller Method I and II.
Miller Method III is a system that uses both software as well as a reflection densitometer to determine proper color balance for printing color negatives.
As in all systems one would have to make a test print of a known tone. A gray card was best. One would also have to indicate in the software if you were using Fuji or Kodak. Having made the test print then one would read the values with a reflection densitometer and indicate those values in the computer program. The software would recommend a new exposure and filter data. If you had the rest of your process under control then within three test prints you would have a proper print of a gray card. The software was using information for Kodak and Fuji gammas for the individual colors and do the mathematics to quickly get one into the ball park.
When the testing was completed it would be used as follows..assuming a gray card standard. Photograph a gray card just before taking photos under the existing conditions and then photograph your scene with the same settings. Process your film. Project your gray card image. Process it and make your densitometer readings. Enter those readings into the software and you would get the information for a properly exposed print of your negative and all others given the same exposure under the same conditions.
So it would go until you ran out of that emulsion batch of paper. Starting a new batch should only require on test and away you go.
Obviously if you were to use for example Kodak Gold Plus film with mercury vapor lights w/o filtration the best that could be accomplished would be a substandard print as compared to normal color balance. If you negative was way under or very much over exposed your prints would indicate that.