No, it is important for you to get a good grasp of the fundamentals. Even if you consult references, like everyone does, without a strong background in the material you will have trouble applying what's in that material.
When I say "fundamentals" it really covers almost the entire engineering undergraduate curriculum. There is so much you need to know in engineering before you can start doing anything of value in the "real world". Most people learn those things in their first few years on the job or in graduate school.
Certainly I agree that one cannot succeed in one's field without deep knowledge of the fundamentals. I just wonder if constant cramming for exams is the best way to attain that knowledge, in place of exercises that actually attempt to apply knowledge as it's learned.
And I'm willing to acknowledge that perhaps I'm not giving enough credit to contemporary engineering curricula, in which much of that 'study' time might be devoted to problem-solving exercises in place of preparing for tests of one's memory.
In my experience, none of the class I (an EECS major) or any of my engineering friends take involve much memorization. The involve understanding a few concepts very thoroughly and being able to creatively solve problems that combine these ideas in really weird ways.
In fact, all of my classes allow at least one sheet of notes to all the exams and I've even had one class that was entirely open-book. Additionally, the graders tend to be rather forgiving for details--thinking consistently is more important.
Even though an engineering degree might be harder and involve more work than something like Political Science or History, the latter two require much more reading and memorizing.
Nevertheless, unless your school is a lot different to the one I went to, there is certainly a lot of memorisation that can be done. You can rote learn the technique for solving a particular problem, just grinding through the steps, without ever really understanding what you are doing. You'll get good scores in most tests, as the tests tend to resemble the practice exams that you no doubt did, but you won't be much use in the real world.
But this doesn't always hold. I remember one class where all of the practice exercises on op-amps were done using an idealised model of the op-amp, without having to worry about things like resistance/capacitance in the op-amp. Then on the day of the test, the professor ran a whole series of questions using op-amps with more realistic characteristics. A huge percentage of the class crashed and burned, because they had just rote learned solutions to problems, but the problems in the exam did not resemble the practice problems. It did however resemble the material that had been taught in class. Those that put more emphasis on understanding what the lecturer was saying than on how to do tutorial problems aced the test. We ended up with a bi-modal result - you either got about 95% for the test (if you understood the principles, the questions were actually very easy), or you got about 15% if you had just learned how to do the practice problems.
The thing that really made that test stand out for me was what it meant in the real world. I went to a military academy, and after graduation we all had to work in uniform for the next 5 or so years, so you got to see how the engineers that got 15% and how the engineers that got 95% in that test fared. It turns out that those getting by on memorisation turned out to be terrible engineers, a fact that I found quite frustrating whilst getting my degree, because their tactic actually worked exceptionally well for most exams. There were only a couple, like the exam I mentioned above, that really cost them dearly.
So, be aware that even if you aren't going down the memorisation route (and I agree with you, engineering should be all about deriving from principles, not memorising tricks), there are others around you that are not doing this. You'll meet those people in your professional life afterwards, and they won't be able to engineer their way out of a wet paper bag, but they will have the same diploma hanging on the wall as you.
When I say "fundamentals" it really covers almost the entire engineering undergraduate curriculum. There is so much you need to know in engineering before you can start doing anything of value in the "real world". Most people learn those things in their first few years on the job or in graduate school.