are fine.
One time I was killing it with a class, had an A average.
There was a test that closed on Tuesday. I went in to take it at 6, apparently for this one test they said they wanted it to close at 4 (just to test us if we were thoroughly reading the instructions).
I explained to my professor what happened. He told me I could retake the test with a 40% penalty (jerk).
I got a 97%, which ended up being a 57% and lowered my grade to a C+. If I kept my pace, I'd get a B even though I thought I deserved an A.
I withdrew, took it the next semester with a different professor, got an A, and was glad I did.