To answer the OP's question, "Is this the nature of the beast?" Answer: yes.
I'm not as avid television watcher as my wife, so it drives her batty when one hour there is a perfect picture and the next there is nothing. Or it begins to pixelate to the point the station is not watchable right at the end or apex of the show and then she "misses it".
In campgrounds, we've noticed when vehicles pass by our campsite, there is often a pixel freeze. And at night, more stations come in.
It's just the nature of the beast. It's still better than paying $120 for satellite television when all you get are commercials anyway.