How to measure productivity of detailers and draftsmen?

My Dear Sir, There is no relation betwen  constriction and drafting in these regards, you can draft a small villa prototyped for1000 units. However drafting time may take only2 or3 days, and the project may last for years

You can measure the productivity of Draftsmen using some units, like detailed tons of construction per week/month or completed drawings per week/month, but didn't forget about construction complexity factor. Etalon of the measure you can define via experience.