In AutoCAD, lack of precision makes later editing, hatching, and dimensioning tasks much more difficult and time consuming. Keep these facts in mind:
In recognition of these facts, a passion for precision permeates the profession. Precision is one of the characteristics that separates CAD from ordinary illustration-type drawing work. The sooner you get fussy about precision in AutoCAD, the happier everyone is.
CAD precision versus accuracy
You often hear the words precision and accuracy used interchangeably, but it's useful to understand the difference. In this book, I use precision to mean controlling the placement of objects so they lie exactly where you want them to lie in the drawing. For example, lines whose endpoints meet must meet exactly, and a circle that's supposed to be centered on the coordinates 0,0 must be drawn with its center exactly at 0,0. I use accuracy to refer to the degree to which your drawing matches its real-world counterpart. An accurate floor plan is one in which the dimensions of the CAD objects equal the dimensions of the as-built house. In a sense, then, it's not the drawing that should be accurate ...