I'm afraid that is how the software works. You still need cut cross-sections and add volume exceptions to calculate quantities along clipped corridor. And then you will need to calculate other elements such as civill cells with driveways, roundabouts, etc.
I think what we really need is a tool to report quantities from 3D model. That would harvest all quantities from 3d meshes and linestrings produced with corridors, civil cells, surface templates, etc. Possibly that tool could categorize quantities by corridors and stationing (in component mesh element info there is stationing data given), civil cell names and produce complete bill of materials.
Collecting quantities from the3D model is most reliable since 3D model is a final product that is supposed to be constructed.