I didn't get to choose. I felt desperate at the time and took flat rates for jobs that seemed fair, only to find that the requirements kept shifting. The client would refuse to pay unless I did more work. It ended up being like $5/hr in the end. Like I said I felt desperate and needed rent money. It sucked.

Another time I'd put all this work into bidding for a job only to find out they didn't really have any money for the project and were just using the conversation to get feedback on their idea.