You may also want to consider the impact of fences on the ability to find wounded game.
In unfenced areas if you shoot badly and wound an animal, you may never recover it. I shot an elephant in Zimbabwe some 300 yards from the Botswana border, which was no more than a road. No fences at all. If the elephant had gone into Botswana, that was it for me.
On the other hand, in fenced areas, you generally know that wherever the animal might be, it's still on the property. In addition, since the landowner owns the game in high-fenced areas (assuming he has the proper permits), then you are generally allowed to use a dog to track the animal. It's not impossible to lose an animal in these circumstances, but it is a lot harder. Of course, the size of the property may mean that even though the animal is still on the property, it might be impossible to find. I recall hunting at the old Wintershoek and another hunter wounding a buffalo. Even with the best rackers and even a helicopter, they were unable to locate the wounded animal.
There are lots of caveats on any statements regarding fences because the bottom line is that "it depends." Yes, the size of the property is important, but so is the animal you are hunting. As
@BRICKBURN says, I wouldn't hesitate to hunt blue duiker on a small property because the size just isn't relevant. When it comes to buffalo, size, though, is critically important. On the other hand, I've culled springbok on low-fenced properties where the animals simply won't jump the fence, even though they could, with ease.
So the answer is to figure out what matters to you, what type of animal you're looking for, and ask the questions which come out of that analysis.