True, I was looking at how a heavier weight is handled in practice. I thought that was more likely answering the initial TS question.
Early in my career, still 2 stripes as cruise reliever on the DC10, I asked the capt if we could do an "optimum" descent, speed around 250 KTS (close to minimum clean speed), would love to see that in stead of the usual 300+ KTS. It took for ages, so we cancelled it halfway, never to repeat that again. I never investigated what would be the effect on range, possible a lot better.