I'm skeptical of that - certainly experimented with it. Maybe the labs themselves weren't consistent. People would slightly underexpose Kodachrome for sake of a little more dramatic slide show; but it made the image harder to print, if that was what was in mind instead. It's when "Kodalux" began screwing up the processing that I stopped shooting Kodachrome.
Ironically, the other film I shot during those days was the pre-E6 Agfachrome 50 - everything "wrong" about a slide film : huge grain, high contrast, poor green rendition, BUT the most convincing earthtones of any chrome film ever. It would even pick up fluorescent algal and lichen colors no other film could. I later printed some of that on Cibachrome, including some of my brother's 4X5 Agfa shots.
A couple of 11X14 inch K 25 prints are still on my walls. But by the time I printed them, I had switched entirely to 4x5 work and Ektachrome 64. Wish even it were still around. No, it couldn't deliver a saturated spring green or pure red, but could handle complex subtle sages and greiges like no other film before or since. It was quite blue biassed. Dye transfer printers knew how to squeeze reds out of it.
Then the Fujichrome 50 revolution arrived,the grandfather to Provia as well as Velvia. Each type had its own personality. I even loved the old grainy etherial Agfachrome 1000.