nostr:npub1acg6thl5psv62405rljzkj8spesceyfz2c32udakc2ak0dmvfeyse9p35c can probably describe better, but I think by Gossip Model we generally mean that the app figures out where to get posts based on the author's write relay list. The amount of connected relays changes significantly over time. That initial description could be expanded to using any relays that are declared in the event kind you are looking for. Public Chats, for instance, should be based on the preferred relay of the channel metadata + relays from your follow lists (so you never miss a follow's chat post even if it's not in the main relay of the channel).