Superfly
Now I think we may be getting somewhere.
As I mentioned IMD is only one of many forces that act on a jet engine as a result of the air’s journey through the donk. A lot of these forces are very dependent on RPM and forward speed. IMD certainly gets bigger as RPM increases and also as the mass flow of the air approaching the first stage increases. But other factors can change whether the overall thrust of the engine drops or increases like the degree of “free compression” inside the intake. (I think if you ask WOK he would probably say that about 50% of his thrust in the cruise comes from the intake effects and not just the fuel burned)
So in direct response to you last post, may I suggest IMD has not gone anywhere, but other things have come into play/happened and the overall engine thrust/efficiency has increased because of these other factors.
JF