I don't know if this will make you feel better, but I hope it helps...

My personal approach was to put the time in and do my best. I figured if I did that, I did enough. You've done that. Make the most of the time you have, and then try not to worry. I figure it's out of my hands at that point.

I never did all-nighters or anything crazy. A good night's sleep is way better than a few extra hours of trying to study while totally exhausted. You'll do better on the test if you are rested, even if there is stuff on it you didn't review. You even guess better.

It's also true that you can study too hard over the course of a couple weeks, or even a semester. Your brain and body need some down time. It can be hard to get, but you can always take a walk outside, get something quick and light to eat, watch a tv show etc.

Sometimes when I, and most of the people in a class seemed to be in danger of failing, and the professor seemed impossible, everything turned out ok. Some professors are just like that. They make you think you are failing, and then you get a "B", or even an "A". Those professors are usually the ones who are decent people, but are always talking about how much they demand from students, and how you are supposed to know "everything".

It's always highly advisable to see your professor during office hours, even if it's only once. They like it, a lot. Come with a few questions, or ask about the final. Sometimes in their office they will even tell you exactly what will be on it!

It's always real stressful, but I try to focus on the work I do, rather than the outcome. You can't really control the outcome. I just try my best. Professors usually respond to that.