I farmed these things with great results for about three days not long ago. Being a newly-ordained RNG, I desperately needed money, and this seemed like a good idea. Let me tell you, my THF31/RNG14 (at the time) was absolutely perfect for farming these. Here are my observations:
- They spawn continuously. I think they spawn on a timer, possibly one every five minutes or so (if one isn't already around). I have frequently killed Rams and moved about a little bit only to find another one very, very soon. Ram spawning has nothing to do with the weather.
- After Lumbering Lambert spawns, there is definitely a delay before Battering Rams spawn again. It's probably about 10-15 minutes. This and the 5 minute spawn time are both estimates; I didn't sit there keeping time exactly. ;-)
- An earlier post already described the spawn area pretty well, but I'll just add my own thoughts on it. The spawn area is centered along the main road. It starts approximately where the road goes through two stair-shaped angles, and continues until just past the break in the mountains where you can go from the road to the lake. The area stretches at all points from the road all the way to the nearest mountains or canyon. Rams *only spawn on the same altitude land as the road*. They will not spawn in a canyon, although they can be trained into one.
As you can see, it's a pretty wide spawn area, and therefore difficult to camp efficiently at low levels, but of course with RNG it's easy. My personal recommendation is THF/RNG. THF must be at least Lv25, so that you have Flee and Treasure Hunter, and RNG gives you Wide Scan. Just patrol the road from the stair-shaped angles to the stone-walled area where Orcs always spawn. Make sure to stray a bit north and south of the road at points while spamming Wide Scan, so that you get a continuous scan of the entire spawn area. When you find it, use Flee and get to it immediately. If it's not taken, congrats, you can easily solo it. Treasure Hunter = drops galore...I have had several Rams give me *7* drops. This adds up to tons of Ram Horns, which, on Seraph, often go for about 1.5K in Windurst. And they sell *fast*.
It's not for no reason I now have nearly 50K in gil despite being an RNG and having to spend obscene amounts of money on arrows. :-D