You would get about twice the MPG gain over MDS by shifting into a deeper overdrive gear instead, but a large fraction of non-technically minded drivers associate “weak engine” with shifting.

Now that most engines have Variable Valve Timing
shifting down to a higher MPH/rpm ratio has even more benefit
because the Dynamic Compression can be re-adjusted for its optimum at the lower rpm
unlike earlier engines that had that “off the cam” weak feeling at too low an rpm because “reversion” had started because the fixed intake valve closing past bottom dead center was now too much.