For example, I'm working on a layout involving large process ductwork (11'-0" ID) with two runs that were both skew to the orthagonal planes and to one another.

I created my sketches (using constraints and parameters), inserted the segmented elbows and supports, and made a set of drawings full of dimensions and annotations. Then, the boss came in and told me the ducts were to be 7'-9" ID instead, and the final work point was to be moved East by 7'-4".

In AutoCAD, I would have to manually delete and redraw my ductwork for the new design, then redraw and reconfigure my drawings. Every work point would have to be recalculated and drawn.

In IV, I opened my master part and changed 3 parameters (2 duct diameters, one dimension). Because of the intelligence that IV allowed me to put into the design, my computer was able to chug through the calculations, projections, and dimensions, and both my model and drawings were updated perfectly in 15 minutes. Every dimension, annotation, and work point changed per the new information, and all I had to do was readjust a few leaders.

BTW: IV isn't really meant to deal with scales like 1/2 mile +. AutoCAD can, because it is meant to be a useable tool for almost any application. IV is meant to be a superior application for mechanical design.