Watching ErictheCar Guy on Youtube, I see that he had to make a judgement call to cut away on a piece of metal to avoid extra steps. The steps that he saved on was removing the catalytic converter and pipe it’s attached to. He performs job starting about 22 minutes in:
Here you can see he is under the belly of the Ford Focus and what part he cut into:
He bent the metal back and out of the way for easier access here. It’s not always the most desirable thing to do, but he wanted to avoid removing the catalytic converter.
He found out that he couldn’t completely remove the bolt after making the cut. But it served the purpose.