NWDI only required on one system?

Hello all, we will be building out our netweaver infrastructure with 2 clusters - a dev, test, prod PI cluster and a NWDI, EP, BI-Java, cluster (dev, test, prod) that will also server as the central sld. My question can NWDI just be installed in one development box and be used/configured for CMS/DTR/CBS for all other netweaver systems in the landscape, or do you need to install NWDI in your test/prod systems as well. Based on what I've read through various documentations/blogs, it only needs to be installed on one system. Is there any benefit to installing it in the dev/test system for future flexibility? We are not planning on seperating the CMS/DTR/CBS services. Thanks in advance.