Hmmm, if I think back on my tests the one that sticks out is sankyu. I learned a lot about myself and my training on that test....because it was terrible
Now, I wouldn't trade that experience. Having a test where I nearly failed (and probably should have) was the best thing that happened to my training.
I know someone who failed his test for yondan in iaido. He was given a list of 10 things to work on. The next time he tested he again failed. This time however the list was down to 5 things. Instead of being bummed over failing he was excited because he'd fixed half of the things that needed fixing.