I once had a large garden away from my house several miles. I hired a man to dig the trenches for pvc pipe and he priced the job before the work was done. The contractor sent out a new man for the job (with a back hoe, no less). I went down and showed the guy where I wanted the trenches dug from the pump house about 200 feet and (around a rectangular garden about 100x100 feet). Hours later and the man never returned to say he was finished, later that afternoon I went down to check on him. He had started out at the pump house with about a 2 foot deep trench by the time he got down to the garden he was down to six feet. The contractor stuck with the original price.