So. I've been working in Blender for a number of years now. And I just discovered something pretty basic.
See, we render frame sequences. This means that each frame is a new file -- typically a .png image. This is better than rendering out a movie in .mov or .avi format because if/when your computer crashes or otherwise stops the render it doesn't automatically destroy the whole render -- you can pick up the render at the last frame the computer was working on.
All this time, though, I was looking in Explorer or Finder for the last frame rendered, and then I would set the first frame to start rendering on that frame, and start up the render again. But it turns out, I don't have to do that!
If you don't check the "overwrite" box in the render panel the render will automatically skip the already rendered frames. The way I thought it worked was that it would render all those frames but put like a "_1" at the end. But no, instead it just does what you want it to do.
Does it make up for the fact that you can't render out shadows without making the thing the shadows are on visible in Cycles? No. No it does not. But it's something.
Under things I must do this weekend:
Render Robot Swarm B
Render Robot Swarm C