I've avoided this thread for awhile because I'm not very familiar with the term piecework. I'm guessing that it's what GCs are referring to when they call & ask for a price per outlet. My typical response is..."Is it a back-to-back outlet, or a sump outlet on a dedicated circuit 50 feet from the panel?".
Typically in this area I'd use the term piecework in new residential construction. I avoid this type of work because there's no profit in it. Usually it's low-bid work at code-minimum less a few required outlets, using back-stabs & cheap materials.
My business is residential service. While I use a price book with listed tasks, I also use my 21 years experience in estimating. While some tasks are repetitive, no two jobs are alike in residential service. The task prices need to be adjusted.
In piecework or contracting the incentive is that if you work faster, you make more money. With T&M if you work slower, you make more money. Honesty & character are the balance. With T&M a good worker will keep the speed up. With contracting a good contractor will use good materials & install with care.
Dave