This question comes up from time to time and the FRC team I mentor used it quite a bit last season to make sure we were not getting burned by the school's "deep freeze" policy. For those of you who do not know about deep freeze, consider it a blessing. All the computers at the school are reset every day and after 40 minutes of idle usage. To compete with this, we'd use the File, Save As, Save a Copy option to create a ZIP on a thumb drive or external drive to make sure we did not loose any work.
This is also a great way to create an archived "baseline" of a particular design. As ideas come and go, so does your CAD design. At a minimum, its a good idea to create a ZIP at the end of a major milestone such as a week, busy Saturday or some other event to capture the work completed. You can then keep all the ZIP's on a thumb/external drive or put them in Windchill as Documents so you always have an accessible backup of your CAD designs as they evolve over time.
The last good use for creating the ZIP is sharing your CAD design with other Creo users when you are not collaborating in Windchill. Windchill is ideally the best place to keep all the CAD files since you have access to all the historical iterations in a single location. When you do need to share the files, using the ZIP method ensures the recipient will have all the files needed to open your design.
