In a previous job, I had a fixed contract for a job.

The contract was for 500 hours.

I had the first prototype done at 43 hours.

It went through 8 major revisions because we didnt have requirements (we literally started with a drawing on a napkin), and the customer was changing major, major functionality between revisions, thus something I shouldn't have been responsible, but it all fell on my shoulders.

I have washed myself of that experience and chalked it up to the corporate world and people having existing relationships with me being the new guy.