Estimating

Creating Military type drawings is an extremely tedious process, no matter what tool you're using.
			  
        AVERAGE HOURS REQD TO GENERATE DETAIL DRAWINGS.
       ADD APPROXIMATELY 20 PRECENT TO INCLUDE CHECKING.
 
     SIZE     A       B       C       D       E
   ------- ------- ------- ------- ------- ------ -------

    SIMPLE    1       2       4       6       16
             1.5      3       6       12      24
	      2       4       8       16      32
    AVERAGE   3       6       12      24      48
	      4       8       16      32      64
	      6       12      24      48      96
    COMPLEX   8       16      32      64     128

Art or Science

Here's an article from "Machine Design" dated around 1972. For some reason I've kept it all these years. It's kind of interesting.