PE, if I get you right, you mean that given a certain film, and given a certain light temperature which we give as normal (the one for which the film is balanced) we should adopt a fixed filtration (determined once and for all for a certain set of film/light temperature) and that should work fine in most situation.
In hybrid work, I suppose this means that I should actually take picture of a known colour patch, create a "film profile", and use that filtration without further ado.
That makes sense to me. It should restrict the need for manual filtration to situation where the light quality differs substantially from the one the film was designed for, or when the filtering is to be adopted to a certain aesthetic - not "objective" - look, such as in situations where we want to arbitrarily choose the degree of reddish/purplish/yellowish quality of light in a twilight image.
This is exactly what I meant by "reference". Color negative can be printed in a controlled process to a "standard" print which yields the standard color balance. Then, this print is a visual reference, just like the slide. Of course, if the light is different, the print will have some color casts, but so would the slide, too!
If you look at the film carton, it shows the color temperature it is meant for, typically 5600K, or 3200K for tungsten balanced films. It means a gray card shot at this light gives a proper gray densities in the film - this is standardized, so it does NOT give some random result as often stated by many. And, when printed, it gives a proper gray. If not, the printing filtration needs to be adjusted. This way, a standard printing condition can be achieved. It stays very constant even with different brands of films. I have seen only one exception; Fuji Reala had to be printed with less magenta filtration.
In practice, for accurate work, many like to add a gray card, color checker card or some other known visual reference in the scene; this is same for both slide and negative.
And, it is worth mentioning how inaccurate "visual references" are. As I stated before, the colors perceived from a slide may vary VASTLY depending on how the slide is looked at. For example, if one looks at the slide with a typical halogen projector, and then the slide is sent to press using cool-light fluorescent light boxes, the result is completely different. Also, different people have different vision, and vision adapts. We have auto white balance and autocontrast in our eyes. This is why I presented difference between big light box, small light box and a masked light box with only the slide area visible.