Is this not all largely academic (especially in relation to a skipper getting the sack)?
I understand the theory behind low CI, early descents and the rest - but to work properly it requires an idealised non or low traffic environment. The realities of airspace structure and traffic often render these early descents less efficient than might be imagined.
Get the earliest possible descent a couple of hundred miles out the second you're prompted by your box? Fine. They just let you down a couple of thousand feet and hold you there. With the end result you're spending time lower down than you otherwise would have, burning a little extra fuel and a hole in your heart. It's a net loss.
It's an idealised solution and you have to account for the environment in which you find yourself. Controversially, this would require some awareness and perhaps even some thought. Given that one can't magic away the traffic, and that you're looking to save a few drops of fuel, would it not be more sensible to descend - yes, at the slowest speed and at the earliest possible - at the earliest point at which you're likely to be able to complete the descent and arrive at the last possible moment? It's not necessarily where the arrow sits on the line.