The problem is, "optimal," is a subjective word. Sometimes what is great for one purpose is lousy for another, but each has its place. That is why there are always multiple bullet weights for each cartridge. And is one reason why the 30-06 is often preferred over the .308W, a better variety of heavier bullets available.
A text book example of vastly different weight bullets being optimal for a cartridge, is the old 6.5 Mauser. In the meat hunting, homestead years of northern Canada, when wild meat was shot year around for people to live on, a 6.5 Mauser had a great reputaion as a moose killer. The bullet that made that reputation for it, in fact the only bullet weight for it made by the only cartridge manufacturing company in Canada, Dominion Ammunition, was the looong, 160 grain round nose.
However, if one were going antelope hunting, or deer hunting where long shots were expected, no hunter would choose the 6.5 if the only bullet available was the 160 grain round nose. The same rifle loaded hot with about a 117 grain pointed bullet would be near ideal for those long shots on lighter game.
