Well how do all these service shops do it? The big dogs, the ESI and NEXSTAR guys with the fancy trucks and TV ads? They pay piece work, and as far as I know, they turn out a nice product.
Everybody has their stories, little anecdotal tales of bad electrical work, these quiant tales prove nothing. In fact, from a statistical standpoint, most of the terrible work done in this industry is done by hourly employees. Using your logic, we can conclude the paying by the hour is more likely to result in poor workmanship.