how many systems in Java Development landscape?

For our J2EE development, we have installed a system with the JDI that we also classify as our Dev system. Our QA system would be the test system.

But in the setup of NWDI systems, there is Dev, Consolidation, Test, Prod. Can the NWDI/Dev system also be the consolidation system? We don't really want to introduce 4 systems because our development activity is relatively simple. I'm still thinking with an ABAP/STMS mind and trying to make the assimilations of how we've done it in ABAP for 10 years can translate to doing the same thing with a Java development environment.