One example, an elevation file. I will draw multiple elevations, interior or exterior in a file, all aligned horizontally with xrefed & xclipped plans above the elevations for reference. These elevations can then be composed on a sheet using viewports. We then need to know, in modelspace, what the viewport boundary is, so that notes don't extend past the viewport, and so that the elevations are consistently formatted.
The trick is to exactly align the viewport to the boundary. My old school method works just fine, I just have to explain to the new people who don't know what a command line is, that they have to type Zoom > L and type the obtuse scale factor. I could use the center point option, but then we have to either draw a guideline to snap to the center, or use a 2pt midpoint snap.