[mechanical_fish]

There's room for disagreement, but I think it's not such a good idea to take 30 units per semester even if you can ace the exams.

It's like everything else involving time: The secret to life is not to work N hours per week, but to work (N/2) hours per week on the right things.

For example, courses with middling-to-poor teachers are just not worth your time: You can watch better lectures online, instead, or just read the textbooks out of the library. And on the flip side, if you find a course with an excellent teacher it's probably worth your time to take that course seriously: Do the readings or the labs, and if you're some sort of ungodly speed-reader do extra readings or labs in that course. (Ask the teacher what else you can do. They will fall over themselves to tell you. That is why they are excellent.)

And if all your courses require no brainpower you need more challenging courses. There are always more challenging courses. After all, even if you're some kind of super-genius who has taken every course and is now bored, you can always invent new courses.