exodus said:
Space goes on forever in every direction, it's that vast. It makes no sence to keep running into the same people over and over again every season, unless they traveling in a circle. Even the Borg don't cover that much space.
Unfortunately this argument isn't quite that simple. The reason is because neither the Battlestar Galactica, nor the USS Voyager are actually traveling around then entirety of the infinite Universe. Similarly they were both heading in a specific direction, and being chased by intelligent life.
Let's bring this down to a more understandable scale.
First a quick story (it'll be relevant later in my argument)... A friend of mine who lives in a suburb of my city (about 10 miles south of downtown) saw a Kia Spectra with a big ass grill-guard on it, thought "WTF" and took a picture of it showed it to me and we laughed about it. A week and a half later I saw the exact same car on my way home from work in North Kansas City (about 5 miles north of downtown). My point with this story? I live in a city that it should be rather unlikely that I'd run into the same perfect stranger, but I did on pure random chance. Now, if I was actively looking for and following that guy, I guarantee you I could do so no matter where he went, even if he left the city for say New York. Now, let's say he went clear over to London, that'd be harder to track, but I could still do it, because I'm actively tracking him.
The reason the argument doesn't hold (still using the small case) would be if I were following him then completely lost him over a time frame that would allow him to travel only a specific distance, but (like the Kazon or Cylons) I know where he's headed. I'd have a much harder time finding him, but I wouldn't need to wonder where in the entire world he was, because he couldn't have left a certain area (air planes and such not withstanding -- since Voyager and BSG have only one means of traveling through space and definitely couldn't have made it 100000000 billion light years away). Even if he was actively trying to lose me and not heading to a specific location, I'd still have a small area that is smaller than the whole planet to search to find him.
So back to the huge example of the universe.
The Kazon knew where Voyager was headed, knew about how far they could have traveled given the time and tech they had, so determining approximately where they are wouldn't be 1 in infinity, it'd be more like 1 in 10 or 20 (random number, but you get the point). And same all goes for the Cylons and their chase.
Now, don't get me wrong, there are other problems with the Kazon being able to keep up with Voyager, but the "infinite universe" problem isn't one of them.