I was asked the other day about how I would go about setting up projects in Project Navigator for Phased work or for Modernization work. Phased work and modernization are similar in the aspect that they are both dealing with stepped processes dealing with existing drawings and coordinating your work between them. They are vastly different in what is done for work, both in the office and in the field. Provided you are using Project Navigator (PN), this will help alleviate some of the headache of trying to keep files organized.
For phased work, I personally would start the project with a defined set of classifications to help in separating objects that do not need to be scheduled. Outline the main phases and base your classifications on the phases. As for PN, you could use divisions for each phase, but I find that gets a bit tedious. I would be perfectly comfortable keeping all phases under one division. The exception to this would be if different phases overlapped into parts of the building already built - I.e.: Phase 1 is the exterior shell and phases 2 is the interior finishing - or something like that. Then I might consider using divisions, but even then I would be hesitant. Another approach would simply be to use folders in each part of PN (elements, constructs, views and sheets) to identify the drawings of each phase. Either way you approach it, the drawing file names should all be unique to the phase they are associated with (I.e.: phs1, phs2, etc. should be included in the file names) for archival purposes down the road.
For modernization work, what you do may depend on what needs to be done with the legacy drawings. In the typical scenario where the old drawings must remain un-touched for archival purposes, simply make a copy of the original project. If it was previously done in ADT using PN, see if you can re-use the existing PN project as a base for your files or simply import the old drawings you need into element files. If working with the copy of the old files, you can either edit them directly to reflect the changes, or xref them into new drawings and use them as backgrounds (which you might want to do if you need to show part of the old building as screened that is being untouched by the modernization). Here you will begin to see the similarities between Phased and Modernization work. You can again use classifications to help in separating objects that do not need to be scheduled. Whether you are using old drawings as a background or editing them directly, you need to make a distinction between the old files and the new ones so they do not have the same names (leaving the old files named the same, but appending mod1, mod2, etc to the new file names). Again, use of divisions are optional in my opinion, I would prefer to use folders in each part of PN as it is a bit more visual for me.