It sounds like the pace may be the differentiator at top schools rather than the difficulty of the material itself. I think D18 would be okay in that scenario (assuming she gets her time management under control). What I don’t want is a ton of busy work dumped on her.
@Magnetron - Was your EM class an advanced one? I took “Electromagnetic Engineering I” in Fall junior year as an EE at UT-Austin back in the Stone Age. It was dreadfully boring with Smith charts, etc. Got a “D”. That disaster turned out to be pivotal moment in my life.