These were some of my favourite as a young freelancer (long time ago): they'd pay me $90/hr to write stacks and stacks of code with our small parents-garage team and when we finished, we demoed to the client who were very happy. But instead of having to wait for bugs, fixes and addition, we just got a new assignment after learning 'great job, but this is no longer needed'. Now I find it painful, but back then we could just focus on 'new things' like that. It didn't happen often, but there were a few large ones that I remember well.