I can see how that works in theory but have you never experienced changes in wind and/or temperature that result in a situation where your only option is to descend as the thrust available can't pull you out of it?
Yes, well below max altitude due to moderate turbulence. At close to max altitude, no, because I don't go there if it to be expected or is forecasted.
I am yet to see a similar post from you admitting that min thrust required does not give you MRC. I have to admit that I'm not holding my breath.
The best source I can dig up on google to be able to provide you with a link is this:
Maximum Endurance, Maximum Range, and Optimum Cruise Speeds
Not the best source, but have a look af the lower curve on figure one anyway.
3/ min thrust required = MRC......we still disagree, I say MRC is faster.
Even if your were right, it only makes my case stronger. It would make the margin even bigger. Since Min Drag Speed would be even lower, than cost index 0 speed. But have a look at the link above.
At the end of the day I think you are simply comfortable with lower margins than me.
I am comfortable with lower margins when I don't need them. If I need higher margins I will take them (more fuel, lower altitude etc.). But there has to be a reason....