Mobile eBay has access to new listings instantaneously, as far as I can tell. I assume it has to do with the way it pulls search results--guessing via the API. On the other hand, the web interface is an absolute crapshoot.
Again, guessing, but I believe API calls will pull search results instantaneously, regardless of location. In the past ETF sales I've had the item pop up in mobile right away but not on the website until after they were sold.
Further, you're kidding yourself if you think these unannounced sales are going to "lucky" people. All sold within 20 seconds, and no announcement? They're running software that's pinging search results at the very least. Note that a page refresher is not enough.