Just an idle thought....
Some years ago, I thought I'd try my hand at colour printing. As it happens, I never got round to doing so. But something has always puzzled me. When it comes to printing, why must the filtration be adjusted for each individual negative. Surely, the filtration would be the same for different subjects taken in broadly the same type of light. Obviously one would have to filter out major colour casts from let's say a tungsten light source. But otherwise, once a suitable filtration had been found for the neg/paper/light source/chemistry combination, would this not apply to the remaining negs on the film.
Regards (at the risk of sounding really thick), BLIGHTY.