They used to rotate the event every year all over the country. Belmont, Gulfstream, Arlington, etc. Each track has a different configuration, different weather, and other different variables.
In my opinion, it made for a better event, was more challenging to bettors, which means better opportunities for long shots.
For example, European turf horses are perceived to be way better than the Americans. So they tend to dominate at the “perfect weather” tracks out West. And the bettors know this so it makes it difficult to catch them at a big price.
However, get them at a humid track like Gulfstream and it kind of evens the playing field. They don’t perform well in humidity since they are not used to it.
These days, they hold they event too often in California, because if the perfect weather and to appease the Europeans. I am against that.