You may have already found out why CAD has many advantages over manual drafting. One big advantage is that once you've drawn something, you shouldn't have to draw it again. If you manually drew a house plan, you would have to draw a front elevation, side elevations, and possibly a perspective view. With one 3-D CAD model, you can generate views from any angle either inside or outside the house. Afterwords, if your client needs something changed, you can then make the changes once. If you're drawing mechanical parts, you can generate virtual prototypes or even create rapid prototypes.