The EDRM diagram represents a conceptual view of the e-discovery process, not a literal, linear or waterfall model. One may engage in some but not all of the steps outlined in the diagram, or one may elect to carry out the steps in a different order that shown here.
The diagram also portrays an iterative process. One might repeat the same step numerous times, honing in on a more precise set of results. One might also cycle back to earlier steps, refining one's approach as a better understanding of the data emerges or as the nature of the matter changes.
Source: EDRM http://edrm.net/