Here the prefab marks you that will appear alone with nothing around and in the mountains, but you can change it to citycenter, smalltown, industrial, etc. and it will appear in all these areas, it depends on which one you choose to add, if you put unique only at the end, Only one will appear on the entire map, but that is left only for large prefabs.
That's what I use with nitrogen when generating maps, the vanilla process takes too long.