Engineering classes seem to be frontloaded more often than physics. In physics, I could generally stay abreast by paying attention. In engineering, I have to really go for broke the first three weeks, and then I can focus on the day to day work after that. But if those first three weeks get away from me, I am lost.
The uncontrolled source of error is the awful quarter system, whereas my physics classes have all been in semesters while engineering has been in quarters.