It will fire for the feed selected up top. If it is "All Follows" that means all pubkeys + t tags + g tags + communities + chats you might have "joined" it is in your kind 3. 

Here is the code that assembles the Home feed REQ: https://github.com/vitorpamplona/amethyst/blob/main/amethyst/src/main/java/com/vitorpamplona/amethyst/service/NostrHomeDataSource.kt