I don't know what's going on in the US system, but what you describe sounds rather broken. In Germany (where I live and regularly volunteer as a polling worker)

I don't know what's going on in the US system, but what you describe sounds rather broken. In Germany (where I live and regularly volunteer as a polling worker), a larger county does not report slower than a smaller county. "Larger county" would just mean "more polling places" so that each polling place maps to about the same number of voters, therefore the load is distributed smoothly. The longest line I've ever seen in a polling station was 10 people who showed up in a group, and it took only 5 minutes to serve all of them.