For jets, the max range speed is in a range where speed stability is very low. Picture yourself the diagram showing drag (vert) for speed (hor). At speeds higher than minimum drag, speed stability is positive: that is, you have to add power to increase speed. At lower speeds, the airplane is speed unstable: you have to add power to fly slower.
At the speed for max range, especially when the airplane is light, speed stability is too low for comfortable flight (lots of power changes). LRC-speed is about 1% higher, which increases speed stability sufficiently for comfortable flight, while having only a minor effect on range.
Erik.