One aspect to consider is organization of your design, including managing changes. I see Rhino as a hobby, and use it for designs for my other hobby, designing/building/flying model airplanes and -sailing the odd model boat. But I work closely with a small company who does this for a living, and uses cad/cam to manufacture kits.
What we found is that when the parts count is high, it is very easy to lose track of the status of all the flattened surfaces. The workflow we follow is design the model in 3D to a reasonable state of completeness, extract the parts as flattened surfaces, build the prototype and test it, change the 3D model as necessary in multiple steps (i.e. correct errors during building and make changes resulting from testing) and extract/replace the flattened surfaces as often as necessary.
We use numbered sub-layers for each part and its flattened equivalent, this way it is easy to check whether all parts are done. If you are not sure if a certain part has been extracted, just look at the layer it is on and choose “select all objects on this layer”, and check if the relevant part is selected in your collection of flattened surfaces. I also developed a simple script to label all flattened surfaces with their layer number as an easy reference, and another script to label the parts in the 3D design in the same way, creating a visual cross reference…
Max.