I have renegotiated terms of almost all my freelance contracts. Usually, a non-compete was the main culprit. Generally, the non-competes don't come from the client, but from a mediator that wants to prevent me from bypassing them and working directly for the client, which is fair. But sometimes they're still ridiculously broad. For example: I'd already worked for a major bank, quit that project because of a new baby, and when I looked for a new project, found one at the same bank through a different recruitment agency. They wanted a non-compete on all my work for that bank. That was obviously not fair, so I got it reduced to only the department where I would be working. I'd be free to work for any other department.