I did one of these jobs about a year ago. Someone did the ruff and supposedly the owner fired him.
Not sure what went on, maybe a little of each side. What I do know is the guy ran all the homeruns and didn't mark any of them.
Also, I couldn't find a couple of them. I broke out my toner and found them just dead ended hanging under the house, connected to nothing.
I told the owner to start with that I would do this on T&M. He didn't like that much and wanted a price. I tried to come up with a worst case scenario price and he didn't like that either.
Finally he said go ahead with the T&M. He said he and one of his guys would help to keep the hours down. I didn't like that but reluctantly agreed.
After I was finished, the total T&M was more than the set price I gave him. This was mostly because they neither one knew what they were doing and I had to constantly stop what I was doing and show/help them.
Also, when I powered up everything, there were a couple of circuits that only part of them worked. I found some buried boxes behind the sheetrock that weren't tied in.
So I learned from that if I ever (doubt it) do that kind of job again, it will be T&M or not at all!