Some stuff you just have to drill until it makes sense. Ordinary differential equations was a bit notorious when I studied. Most people took 50-100 hours of dri

Some stuff you just have to drill until it makes sense. Ordinary differential equations was a bit notorious when I studied. Most people took 50-100 hours of drill before they could solve them reasonably competently (enough to get an A). For me it was that and some of the control theory stuff that to this day still seems like a dark art. Other stuff once you understand it the exams are straightforward, if tedious. Antenna design was like that for me, I'd solve it geometrically in my head then work out which transforms and equations matched my solution. Other people just ground that stuff out along with all the rest. I hope no-one was twisted enough that ODE's made sense...