Certain developers may get closer to the three

Barry Thornton makes much of that triangle in the Edge of Darkness.

I'm not a fan of Barry Thornton's writing but some is very sound, but as Voltaire said "I disapprove of what you say, but I will defend to the death your right to say it."

Staining developers seem to be a modern key to achieving the optimal balance, in many ways it's a neglected area. Edwal was once pre-eminent in this field, Johnson's the oldest of all photo-chemical suppliers another and had one of the best with Meritol, the PPD/Pyrocatechin developing agents but our own Sandy King has (along with GH & PMK) revived the staining developer with Pyrocat HD which is like Rodinal on Steroid

Some of the very best developers were made by smaller companies with some superb formulae. But even Agfa with Atomal, and M&B's Promicrol were nudging into the magig triangle.

My own feelings are that at the moment Pyrocat in it's various forms is the best optimised developer for modern films

Ian