Civ V: Tradition Follow-Up

I was playing some single play Civ V while watching a FFVIII speedrun this afternoon when I got to select a new policy. I didn't have tradition yet in that game and I had 8 cities in various stages of advancement so I figured it was a fine time to test to see if I could figure out what exactly the tradition policy does in terms of border growth rate. I saved in case it ended up being as bad as my searching yesterday indicated it was going to be...

The first thing I noticed while writing down the 'next cost' for each of my cities was how wildly they varied. I tried counting all of the adjacent spaces that were under my control but couldn't really find any rhyme or reason to it. Several of my cities bought land and a full half of my cities were obtained by conquest. Other cities in the area were burned to the ground. So it's possible that some of the squares were obtained by cities that no longer exist or something, and it's possible bought squares are treated differently than earned squares. So when it comes to finding out exactly what is going on... No dice!

But when I went back and tracked how the costs changed when I gained tradition it was obvious that while I don't know exactly what is going on, I do know something significant is going on.

Squares Previously 'Earned'	Next Cost	Next Cost w/ Tradition
13	190	60
9	105	40
5	120	45
4	40	25
16	260	75
14	120	45
13	85	40
5	70	35

One of the cities (a capital I conquered) managed to knock 71% off of the cost of the next square! My own recently settled small city 'only' saved 38%. Most were saving in the 65% range. When the game says signficant it isn't lying!

So the secondary benefit of tradition is actually a real thing. Assuming expanding your borders is a thing you care about, it's a really insane boost. The question then is how much do you care about expanding your borders? Getting a few expansions fast tends to be pretty clutch because often I settle 'near' resources I want but not right beside them. The AI is pretty good about bee-lining towards those, though. After a city has a few really good squares to work it really doesn't need any more unless you're making your cities really, really big. (And if you're making your cities really big you probably need the rest of the tradition tree anyway.) I like expanding my borders against the AI because it keeps them off your land. I like expanding my borders when I'm settling near other people because squares I control are squares they don't control. But in the game where I did this test I went on a warpath early and I don't think I care that I don't own ALL of the land around my cities. I burned all the other cities nearby to the ground so no one owns it. Expanding your borders is actually also a downside if you're trying to farm barbarians for culture with the honour policy since encampments disappear if they get inside your borders.

In my current game I kept tradition because I didn't really want to reload, the 3 culture in my capital isn't nothing, and I just like seeing big borders. But I feel like it wasn't really needed. I still haven't needed to choose a 4th policy in my main multiplayer game so I haven't been put to that choice yet... Is expanding my borders fast against humans I've yet to meet a thing I actually care about?