i would never do that with a bird. They're too large and if you're off by just a little bit it's excruciating. We did this to frogs in college anatomy lab. You have to be quick and sure. I would definitely choose something else for chickens.I was thinking the same.
I've always thought pithing sounded awful, and I could never bring myself to do it. Your experience just reinforced that feeling. I'm sorry you had to experience that.