For nearly 20 years I've used the same process I developed at some huge firms as I now use in my small practice: separate model files for each "slice" of model information. The NCS provides for this option. The trick is that it is MUCH easier to manage objects between files than across layer names.
For example, A-XP (existing), A-DP (demo), and A-FP (floor/new). You can cut/paste-in-place between the XP and DP in five seconds. Moving objects back and forth across layers with status designation tails (-DEMO) takes much longer.
The approach helps the team manage a very large info stack, assists in manipulating lineweights and types by XREF, and atomizes the amount of info in each file so that larger teams can all be working on a project at the same time. File writes and cloud updates are faster, and less needs to be transmitted in minor updates. But the biggest advantage is organizational.
NCS didn't provide as simple a method for additional parametric slices, so we extrapolated: CX, CD, and CP are ceiling eXisting, Demo, and Plan. Same goes for RP (roof plan), SC (sections), EL (elevations), DT (details), EP (enlarged), and so on.
And by "manage," I don't just mean keeping object status straight. If you plan ahead, you draw your plans stacked about 0,0,0 in some fashion. Then elevations are drawn *below* the plans so that they can reference it, usually with copies of the originally positioned XREF plans "twisted" along for each elevation. Then sections can be drawn over the elevations. And details can be drawn over the sections and plans. I use tails to designate scale for details to further segregate annotation. (I dislike auto-scaling annotation because I still have to go through and tweak it for each scale anyway in the rare instance I reference it more than once.) Develop a clever XREF model file coloring routine that automatically pounds XREF layers into prescribed colors and light weights based on model file, and perhaps floor level, and you instantly know what every piece of the large stack is that you're looking through no matter the model file you're in. Use an intuitive color scheme that casts each type of file in it's associated hue area on the color wheel. Saturate new work and darken/dash demo versus existing for renovations. We sometimes create a master reference file that embeds all the model files just to double check design logic and drawing execution, but this is never used for authoring.) Develop them for sheet files, too.
About the only kickback I've gotten over this scheme across the decades using it are from the "folder people" who like to make endless subdirectories that make managing XREFs disastrous. Don't let them win. I've seen very, very large buildings executed with all the model and sheet files in the same folder simply by teaching everybody how type-ahead works in a file manager and file open dialog.
Custom menus with shortcuts for all this is available in LT via CUI and scripts if you do it right. Cheap, fast, and easy. Which is really the best way to do great design, avoid mistakes, and go home on time.