No its not about getting it all on paper, you are making several assumptions, the colour separation decreases with exposure on the negative. Tones start to compress even at +1 stops, regardless of what you want to believe, you need to give it a go and analyse the actual negatives.

Extra exposure increases density, hence you get a thinner image on a denser negative. Minimum density increases faster than maximum does with increased exposure. This also causes increased graininess.