In company I'm working for, architects don't model 3d models for designing. They don't have enough time for that :) So they bound to use my 3d model, modeled in 3dsmax for designing purpose. They're getting measures from it, estimating forms and volumes, and they often need sections from the model. So Section spline object is very useful in architectural modeling process.

Section can be converted to spline by pressing "Make spline" button, but what if you need to convert hundreds or more sections to splines? It's very simple, you can convert as many sections as you want at once - just select them, press right mouse button and choose "Convert to editable spline". Then these splines could be collapsed to one by "Attach By Name" command in any spline modifier. By default converted spline have "Section##" names, so selecting them in "Select by name" window not a problem.

You can use this technique to model roof folds or something like that. Create section with Array command, convert them to spline, collapse in one spline, Extrude them and add Shell for thickness.

One problem after converting is that converted splines have many unnecessary vertices on the straight segments. I'm using this trick very often, so I've written the script to get rid of the vertices on the straight segments of the spline - here it is.