Very few organizations would ever consider deploying something such as SCCM 2012 and SCEP in their production environment without kicking the tires first. Typically, what's done long before a decision is made to buy the product is something called a Proof of Concept (POC). During a POC, SCCM is installed in a lab environment that has its own AD domain and subnet.
It's always a good idea in the lab to have some workstations that are built off your corporate standardized image. This will allow you to deploy the SCCM and SCEP clients and give you the chance to verify that the clients are not going to adversely affect your applications or hamper the user experience.
Conducting a POC in a lab is not quite the same thing as building out SCCM and SCEP in a development environment; if you work for a medium to large-scale organization, a single SCCM server in a standalone primary site configuration would not be very representative of your production...