Duplication occurs when multiple installations of like products result in saving installation time. Fixtures in the same concentrated area, parallel conduit runs and multiple conductors in a raceway are all examples of possible deductions for duplication. My pet duplication is multiple conductors in a raceway. Most labor units that you see are for one conductor in a raceway. Most contractors will admit that feeders are where they make their biggest profit, and here is a good reason for it.
Project management is the answer.
After the estimator wins a bid, someone has to produce the project. With an accurate estimate, the project manager has documentation for creative management. Allocating labor resources is critical. Under or over-staffing a job typically affects the bottom line. Project managers need to know specific labor requirements for each phase and task of the job.