Looking it up I was actually remembering from Feynman's QED book (path integral approach). I don't have it at hand but I think it's a description based on photon particles. Anyway I agree my description with photon travel "between atoms", emission and absorption was quite bad (especially if you think absorption and emission as slow incoherent processes instead of a general way of describing interactions which is what I meant).

But still I think saying "the primary wave gets absolutely and completely delayed" is not helpful. Using a wave description as in Feynman's lecture[1] is more enlightening: the incoming wave travels at "full speed" through the medium, but doing so it interacts with atoms such that they emit an additional wave, and the sum is a slower wave.

You can say it's the same since there's only one electric field in space and so the only "real wave" is the sum of all effects. But I find it quite helpful to think that one of the components in this sum is the original wave traveling at the speed of light in vacuum, also in the space occupied by the medium.

[1] https://www.feynmanlectures.caltech.edu/I_31.html