The second point is a good one. My workhorse desktop is rarely connected to the network. It has dual monitors, and both monitors are shared by another computer

The second point is a good one. My workhorse desktop is rarely connected to the network. It has dual monitors, and both monitors are shared by another computer that is connected to the net. So it's easy to switch either screen from workhorse to web browser or whatever. I can't cut/paste between them, but it doesn't hurt that the sneaker net is in the same physical location and even shares the same screens. I rarely need to do that anyway. When I'm working on my laptop, I simply take what I did for the session and thumb-drive it to the workhorse later. The workhorse desktop is my "de facto" source, so it is the only one I bother backing up.