You're right that once you saturate your green cones, the marginal response of other wavelengths will overtake 550nm. But until you hit saturation, the most eff

You're right that once you saturate your green cones, the marginal response of other wavelengths will overtake 550nm. But until you hit saturation, the most efficient use of energy is to put everything on 550nm, not spread it out. You're saying that changing the response curve (e.g. by saturating the green cones) changes the optimal wavelength, but that doesn't change the fact that there's always a single optimal wavelength that is the argmax of the current marginal response curve. In any case, we're talking about displaying color on computer monitors here. If your computer monitor is getting anywhere near saturating your cones, you have a big problem.