Exporting for paper
The file that looks right in a browser is rarely the file that draws correctly. Two exports, two purposes.
Plotters want paths and nothing else — no fills, no strokes with width, no groups nested twenty deep. Flattening everything to open polylines before export removes an entire category of problem at the machine.
Overlapping lines are the expensive mistake. The pen goes over the same place twice, the ink builds up, and the paper eventually gives up. Merging coincident segments before export saves both the pen and the sheet.
For the web version the opposite is true: keep the structure, keep it small, let the browser antialias. The two files stopped resembling each other a long time ago.