It's not silly if you never paid attention in any of the classes and you're learning the stuff for the first time. I know that's happened to me before, especially for a lot of the easier courses. Some knowledge that has a high probability of not being retained is better than no knowledge. :)

This is of course a stupid solution to a completely different problem, but those courses didn't inspire me to try my best... if I had another chance, I don't know if I would try harder. I know that sounds bad.

I can vouch for this. Best thing to do before a test is sleep! If you're too nervous, go to bed early at least so you can try to get some hours in before the morning.

I've never remembered anything after a cram. And really, if you're only studying for the exam (and we know how much of school knowledge we use in the real world) then school is pointless if not for a piece of paper you get at the end.