Thanks. We just revisited this over Thanksgiving (last Thursday) with Carpano Classico and Tempus Fugit Bitter. I frequently find "equal-parts-of-everything" cocktails to be muddy and overly sweet or imbalanced. It seems to have been a thing back in the early days of mixology, when all of this was new. Building a drink by choosing a base liquor (even a split base) and then adding smaller, designed amounts of flavorful and sweet/sour/bitter contributions chosen for their ability to play together nicely elevates the added ingredients as well as the base. The 4:1:1 Valentino proportions are pretty lean but 2:1:1 seems like a good starting point for many drinks with a base and two complementary additives.
Interestingly my final proportions were 40:30:30, bearing on mind that this were a modern take on a classic, splitting the Campari with select lightened it and I hope to it closer to it closer to the intended flavour.